The moment came on about day four. A cloud-like mist was drenching our faces, hair and clothes, despite the thick canopy of trees overhead. My six-year-old daughter silently trudged uphill pushing her bike, her mouth set in a grim line. I looked again at the blue blob on Google Maps, which seemed, unfeasibly, to indicate we were on the right path. I thought, again, about the diminishing supply of chocolate in my backpack.

“See! I told you! We’re having an adventure,” I said with forced jollity. She didn’t even look up.

“This is not an adventure,” she said. “This is just pushing your bike up a big hill.”

Adventure. Such an intoxicating word. And so easy to achieve … when you’re young. But with two kids, within the constraints of the summer holiday? Well, that’s more of a challenge.

It was with that quest in mind that we found ourselves lost up a lush, densely wooded mountain in the Spanish Basque Country, on a track unsuited to bikes, as part of the first stage of a three-week road trip from Bilbao in northwest Spain to Saint-Malo in Brittany, north-west France.

I’ve always loved a road trip, and was hoping to recreate – in some limited way – a classic that I had done in my 20s. After living in Paris for two years, I and my then-boyfriend meandered across France for a month in my nan’s old Peugeot, camping in different places virtually every night. We stayed in fields where we were the only people for miles and watched eagles swooping as the sky darkened; we begged the manager of a stuffed-to-the-gills campsite to move his car so we could camp on his front lawn.

This would, of course, be different. My partner is deeply sceptical of camping. The kids still shudder at the memory of the toilets on the first campsite we ever stayed at. So how do you have a somewhat unstructured, kind-of-spontaneous road trip with kids?

We decided on a mixture of home swaps and posh camping, and started with a journey that is an adventure in itself. On board the two-night ferry from Portsmouth to Bilbao on Brittany Ferries’ Galicia, we spent hours watching pods of dolphins, reading our books, and sneaking back to our cabin for naps. It’s worth noting that while entrance to the first-class Commodore lounge isn’t cheap (prices vary by ferry; it’s £79 a person on the Portsmouth to Bilbao crossing), the excellent buffet is endlessly replenished; all drinks, including wine at meal times, are included; and the lounge is a peaceful haven.

We rolled off the ferry, kicking off our escapade in Bilbao on the opening day of Aste Nagusia, the city’s annual nine-day party. After a stroll around the Guggenheim – arguably the best modern art museum in Europe – we headed to the Plaza Nueva in Bilbao’s Casco Viejo, where the pintxo bars were rammed with locals wearing blue and white checked scarves and shouting for more cider. The Spanish know how to live, but the Basques? They know how to party.

Full of anchovies, olives and salt cod, we drove north along winding roads up into the verdant mountains of the province of Gipuzkoa to our first stop, an apartment in the small hamlet of Berastegi, about 25 minutes from San Sebastián – a stay organised through the home swapping website Home Exchange. We are evangelical about home swapping, having saved thousands of pounds since 2022 with brilliant holidays in Spain, France, Denmark and the UK.

You frequently discover fabulous places you might never have heard of too, often on the recommendation of your hosts – such as Casa Julian, in charmingly sleepy Tolosa, where we ate a steak so good as to render all future steaks redundant. A devastating steak, frankly. A meal for four cost €234, and I would happily sell my car to eat there again.

Staying in Berastegi also allowed us to visit the bustling city of Pamplona, a 40-minute drive away, where we drank unctuous hot chocolate in Café Iruña, Hemingway’s old haunt, before learning about the running of the bulls on a grimly fascinating tour.

The money saved on accommodation also meant we could afford a night in a hotel in San Sebastián, where we ate, strolled, swam, then ate again. The city’s claim to have the greatest density of Michelin stars in the world is disputed, but when you are drinking a glass of cold txakoli and hollowing out a stuffed txangurro (spider crab) that hardly seems to matter. Kid-friendly trips to the cool aquarium (vital information: it has axolotls) and the 113-year-old Monte Igueldo amusement park were interspersed with a copious €20 menú del día at Aldaba. Something for them, something for us.

Full, again, we took to the road, driving away from the mountains via the delightful French Basque coastal village of Bidart to our next stop en route to the French Atlantic coast.

Two hours from the traditional timber-framed baserri (farmhouses) of south-western France, the mist-shrouded mountains give way to the open flatlands of western France, long wide roads lined with pine trees and dunes that rise up from the crashing waves of the turbulent ocean.

We stopped in Arcachon at the Huttopia site, one of a family-run chain of nature-immersed campsites. The handsome seaside resort, with its 19th-century Arcachonnaise villas with names such as Esmerelda and Denis Papin, feels like the stately grand dame of the Atlantic coast.

Our luxury “évasion” chalet, with its nice toilet, strong shower and comfortable beds, was not, let’s face it, camping. But, nestled among the pines and deep in the forest, we sat on our deck listening to the soothing throb of crickets and got similar benefits, only without the discomfort. When we climbed the awesome Dune du Pilat, it felt like landing on the moon, and when we held hands and hurtled down it again, like we were taking off into space.

Three days later, the landscape transformed again as we drove to the flat salt plains of the Île de Noirmoutier, about one-and-a-half hours from Nantes, and set up home in a well-stocked Huttopia wood and canvas desert tent, next to the water’s edge and a short walk from the village of tiny white bougainvillaea-draped houses and restaurants. That night, as I sat outside the tent listening to the waves and the wind in the trees, I looked at the stars stretched out across the inky sky – and I remembered those eagles.

To complete this family odyssey, we spent four days at another home exchange in the underrated Breton port of Saint-Malo, which has a wealth of charm, great food and delicious cider – as well as the most delightful coastal pool I have ever swum in.

On our last day, we went to Cancale, where I had tasted oysters for the first time, scooping them up from a plastic tray, with a glass of sancerre, on the beach. This time we opted for a restaurant, and while my son learned to slurp oysters, my daughter tried her first mussels. As she used an empty shell to pinch their juicy flesh and pop them into her mouth, I recognised that I get as much pleasure from their discoveries as from my own. And, I thought, maybe the adventure isn’t over after all.

Accommodation at Arcachon and Noirmoutier was provided by Huttopia: Chalet Évasion from €75; Toile & Bois tent from €69. Transport was provided by Brittany Ferries: Portsmouth to Bilbao for a car, four people and an ensuite cabin from £490 one-way; St Malo to Portsmouth from £225 one-way for a car plus four people. Home Exchange membership is £190 a year