We had two makerbot replicator 2's at my school, and they worked very well. Like most 3d printers they had their quirks, but we also had an afinia/up, a rapman 3000, and a prusa i3 and they were the easiest and most reliable to use. THey also have a huge userbase and decent customer service to boot.
I'm not sure if it applies in the UK, but in the US makerbot has a program to give schools 3d printers for very little money.