Just ordered some pillow pet type things from Home Bargains (snuggz), if you have one near would be ideal to get some and stock up, they were £3.99 each, my dc all love them, they open up quite large about the size of a normal pillow.
Worth looking on the Book People too, they do collections of books, e.g. 10 for £10, and are good quality books - like the Gruffalo etc. You just have to keep looking as their stock varies.
Tesco have a 25p/50p selection of birthday cards. Also value wrapping paper. I keep stocked up!
I've been giving Usborne "see inside" books recently, the range includes fairies, dinosaurs, castles, etc etc. Lots of detail and flaps for interest. May be a bit old for 3 year olds, you could try the Usborne 'noisy' books instead. I get mine from amazon which I know is terrible for my local businesses but oh so convenient...
Dd1 has quite a few parties coming up, having been invited by friends in her pre school class. They're turning 3 this year. Obviously I don't know these children yet, so I wonder if people have ideas for presents to take? I'm thinking maybe a book or game/jigsaw would go down well, as they're the type of thing you can always have more of. Also, where's good for getting these things reasonably? I'm thinking I should stock up on a few girl/boy presents. Hoping to spend no more than £10 a time, inc wrap & card.