duxbuz:
I was just going to get entry level Uno, but the one for £23.68 caught my eye as I though built in wireless might be worth having
It is usually a lot cheaper to get a basic Uno and add the shield you want later. This particularly applies if you aren't sure what you want, which appears to be the case, and the number of options is closer to six. Further, by the time you get to using any radio link, you might be wanting a Mega anyway.
Generally, WiFi is used to communicate with the outside world while Xbees etc. are used to communicate with equipment. Xbee is an expensive but versatile system which covers various types of transmission. If an Xbee shield costing 13.49 didn't acually talk to anything until you added a radio, it wouldn't surprise me.