I have never been so relieved to see a caravan park in my life, and that includes the time I got caught in a hailstorm near Skegness. The drive to Seepark Kirchheim had been one of those classic British-in-Germany experiences where you convince yourself you have mastered the autobahn, only to discover you have spent forty-five minutes in the wrong lane behind a lorry full of turnips.

My sat-nav, whom I have named Brenda due to her passive-aggressive recalculating tone, decided that the most direct route involved what I can only describe as a farm track. A very enthusiastic farm track. By the time I bumped into the actual entrance of the park, my spine had rearranged itself into something resembling a question mark and I had developed a newfound respect for tractors.

The first thing that struck me about Seepark Kirchheim was the lake. Not in the literal sense, though given my coordination that was entirely possible. The Heerwaldsee lay there like a promise, all flat and grey and German, with mist curling off it in a way that made me think of cheap detective films. I had packed for walking. Serious walking. Boots that cost more than my first car, waterproofs in three different shades of sensible, and a hat with a flap at the back that I now realise makes me look like an unsuccessful scoutmaster.

The Hesse countryside around Kirchheim is proper walking territory. Rolling hills, patches of forest, those sudden meadows that appear like someone dropped them from above. I had planned three days of ambitious hikes. The Vogelsberg hills were practically next door, and I had read somewhere, probably while drinking wine and feeling optimistic, that this was ancient volcanic country. I pictured myself striding across lava domes like a particularly well-equipped Heidi.

Day one began with confidence and ended with me in a bus shelter near Ulrichstein, wondering if hypothermia sets in before or after you stop feeling your toes. The British weather, that traitor that followed me across the Channel, had decided to make an appearance. What started as a brisk morning with "character" quickly became horizontal rain that found every gap in my expensive waterproofs. I had walked perhaps four miles when the sky turned the colour of a disappointed teacher and unloaded upon me with what felt like personal animosity.

There is something deeply humbling about being defeated by weather in a country whose language you barely speak. I stood in that bus shelter, steam rising from my shoulders, and contemplated my life choices. The volcanic hills were up there somewhere, invisible behind a curtain of precipitation that showed no sign of relenting. I had seen photographs of this region in sunshine. Golden light on beech trees, distant views of the Rhon mountains, hikers smiling with the smugness of people who checked the forecast.

I did not check the forecast. This is, I reflected, why I am single.

Day two I approached with what the Germans probably have a compound word for: the specific optimism of someone who has not yet learned their lesson. The rain had softened to a persistent drizzle, which in Britain we call "fine" and which in Germany apparently counts as acceptable conditions for outdoor activity. I set off toward the Hoherodskopf, a nearby peak with a tower on top that I had convinced myself would offer dramatic views and possibly a hot drink.

The walk up was magnificent in theory. The beech woods were dripping and green, the paths turned to streams, and my boots made that satisfying squelch that means you have committed to something. I passed a German couple in matching rain gear who looked at me with an expression I can only describe as pity mixed with mild concern. They were walking a dog that looked drier than I was.

The tower was closed. Of course it was. I stood at the base, water running down my neck, and laughed. There is a particular kind of liberation in complete plan failure. I had come to Hesse to conquer hills and see distances, and instead I was achieving a profound intimacy with cloud base. The Rhon mountains, the Vogelsberg peaks, all of it existed somewhere above and beyond a wall of grey that had settled in like an unwelcome relative.

I walked back down by a different path, partly for variety and partly because I had got lost. A farmer in a Land Rover pointed me toward Kirchheim with gestures that suggested this happened regularly to foreigners. I arrived back at the caravan as darkness fell, with feet that had apparently been replaced by cold porridge, and a new appreciation for the heating system.

Day three broke different. The clouds had exhausted themselves, or perhaps moved on to torment someone in Bavaria. I woke to actual sunshine, the kind that makes wet fields steam and turns puddles into temporary mirrors. I walked to the lake first, the Heerwaldsee that had greeted me so moodily, and found it transformed. Families were out, the water glittered, someone was attempting to windsurf with more enthusiasm than skill.

I took the path around the shore, then followed signs toward the Lauterbach valley. The ground was saturated, each step a small negotiation with mud that wanted my boots more than I did. But the light, that low autumn light that comes with cleared skies, made everything worthwhile. The forests of Hesse in sunshine are a different country entirely. The beech trees glowed copper and gold, the distant hills showed themselves shyly, and I found myself on a ridge looking down at Kirchheim with its tidy houses and church tower.

I had not reached any of my original destinations. The Hoherodskopf tower remained unclimbed, the longer Vogelsberg circuits untrodden by my increasingly soggy feet. But standing there, with weather that had finally decided to cooperate, I understood something about walking that perhaps I had missed before. The plans are not the point. The point is being out in it, whatever it turns out to be, and discovering that your own company in a bus shelter can be unexpectedly educational.

I walked back to Seepark Kirchheim as the light faded, past the lake where mist was beginning to gather again, and felt something like accomplishment. My boots would never be the same. My waterproofs had surrendered at the seams. But I had walked in Hesse, in weather both British and belatedly German, and I had the steam rising from my shoulders to prove it.