The children and I set off for a holiday in the early morning. The smell of alcohol on R's breath is so obvious to him and me that we skip the goodbye kiss and settle for a wave. I always look forward to going to my parents' house, and this time I feel both very young and very old.

When we arrive, I sit in the back of my mother's car with the boys. I am suddenly 12 years old again, but I don't mind. My daughter sits in the front so she won't fight with her brothers.

I feel young because I can't afford to pay for a long taxi ride. I am, as usual, broke and this is not so much embarrassing, as it is disappointing. In my teenage years, when my dad would ferry me to and from parties or friends' houses, I would think: "When I'm 20, I won't need lifts. I'll be loaded and I'll get cabs everywhere." I'm way past 30, but I'm still not rich enough for any of that.

As soon as I enter my parents' house, I feel old. Old, because I have separated from R and arrived with our children as a newly single parent. I don't feel like the child of anyone, because surely my recent decision is the stuff of grownups.

I drag my suitcase inside, and glance at the photograph in the hall of R and me on our wedding day. I wonder if it will still be there next year, or – if we are still separated – when it will be put away for ever.

"You're here!" My sister S, who is also visiting, bounds towards us with her children, and we hug. It is so wonderful to be together and the children run into different rooms, immediately picking up where they left off. I scoop up my baby niece and don't put her down for a very long time.

I feel protected by the familiarity of the house and my family. The drill here is so reassuring, the loose routine so appealing compared with the recent long stretches of structureless school-free days that I've had to plan back in London (and I'm a dreadful planner).

Here, I will wake very early some mornings, leave the children to sleep and walk the dogs along country paths with nothing but nothing – save the flora and fauna – for as far as the eye can see. I will enjoy the kind of solitude that I have been craving.

At home, I have lovely friends and neighbours, for which I am grateful. Yet as evening nears, I find myself carrying out all the mundane but necessary tasks on my own, with no one for company apart from the children. Night after night, it becomes isolating and tiresome. It is a miserable kind of loneliness, and come 8pm, I'm often crying out for the presence of another adult: someone to talk to as I sweep up the detritus of a busy day; to eat dinner with; someone with whom I can sit down and enjoy the last peaceful moments of a day's end. I am so lucky to have that here.

When we are together, my sister and I talk about memorable periods of our childhood. Here, we have the aid of photographs, books, toys – there is even the odd bit of graffiti on furniture (amusingly, my eldest son spots the words "I HATE IT ALL" etched on an old dressing table of mine, and I have a vague memory of scratching them on to the polished wood with a compass from my maths set, in one of my more expressive periods of adolescent malaise).

Most major things that have happened – and that I'm reminded of when I'm here – have always seemed fairly recent in my mind. But now I realise they occurred 10, 20, even 30 years ago. I was a baby of the 70s, a child of the 80s. The photographs that my children ask me about – "Is that really your hair, or did you wear a curly wig then?" – seem not just ancient to them, but to me also.

Later, with most of the children in bed – and my sleep-shy daughter sharing chocolate and watching Don't Tell the Bride in the living room with her grandpa – I sit with my mum and sister in the kitchen. We drink wine, eat pudding, and talk. I rock my niece in my arms, as warm, compact and pleasing as a freshly baked loaf. A single fat tear rolls down my cheek, and I wipe it away before anyone notices (and my mother asks if I'm depressed). It makes me think that I haven't experienced happiness like this in a very long time.

Exhausted, we clear up and go to bed, saving further talk of unsuitable underwear and the events of the past year for another evening. It is hard to pinpoint exactly how everything can suddenly feel so right and good again. It's very dark at night here, and I will sleep well, cheered by the thought of an army of my favourite people at the breakfast table in the morning.