Blueberry

I don't but then I live in Cornwall where it is generally milder and we don't get very severe frosts

I only give mine food when it is in fruit and I use a special ericasceus (?sp) liquid feed

I don't either and I'm on about the same latitude as you, Uulwyn. They're a North American plant and are used to far worse winters than anything the UK can throw at them. If you mollycoddle them too much they start to flower in February, which means that they miss the pollinating insects and the blossoms would also be susceptible to a late frost. Only give them an ericaceous feed (it will say it's for Azalias and Rhodedendrons on the box/bottle.) and plant in an ericaceous compost. Your worst problem might be frost damage to the pot, but you can wrap a bit of bubblewrap around it to protect it during the coldest months. I feed mine at the beginning of the season, and again when they are about to fruit, plus any other time that they look like they need it, though I've had mine a good few years now, initially you will probably need little in the way of food as your compost will be fresh and will provide much of the nutrients at first.

Thanks for the info fellow gardeners. When you say beginning of season do you mean the beginning of the year, sorry if that's a daft question.