Does she go to school? Learning Resources does a fabulous pretend and play school set, which my DS (he was 4 then) absolutely loved last year. They also do a pretend and play post office set, wwhich eh is having this year. They are around the £20 mark each.
Playmobil swimming pool would be lovely for her at this age. As would the playmobil camper van, I think. They are around £20 each. The coach/school bus is also very nice for about £20. I wouldn't recommend the aeroplane as it falls apart.
Does she have a camera? The Vtech one is really easy for children her age to understand. And Ds has really enjoyed using his Innotab 2 (which are less than £40 I think, now that the Innotab 3 has come out).
I have heard good things about the Leap Tab readrer (the one with the pen that stores up to 10 or so books on it and says the words as the child points at the words in the book with the pen). That is £40 as a starter pack, and then you can buy further books within her age range.
Hama Maxi Stick is good for her age too. You get a board, pegs and two patterns in a box for £10. You can re-use and re-use.the Melissa and Doug threading animal cards are good for her age too. And DS liked Tap Tap Art at that age (buy an extra cork board if you can).
Would she like the imaginext castle? It has been reduced to £39.99 at some places (there was a link to it in another Christmas thread). I think that is brilliant.