Went into my local B&Q (Newbury Park, Essex) on Saturday and they had about 7 crates of double socket, single socket and switches - all going for £1 each. Great value when the originally cost a lot more. Lots of different designs and colours so impossible to list them all.
They aren't available at all B&Q's because I went to another one on Saturday and they said they don't do clearance lines at that branch. So you have to be lucky. I think some of these may also be available on line.