Hi, a lot of people use fingertech snap hubs and wheels

http://www.fingertechrobotics.com/pr...d=ft-snap-hubs

You will have to root through some of the menus as the stuff is American and so a lot of the screws and circlip pliers are in American sizes. I got fed up with it so I use these wheels, hubs, motors and brackets.

http://www.technobotsonline.com/polo...lack-pair.html

http://www.technobotsonline.com/polo...pack-of-2.html

http://www.ebay.co.uk/itm/2-x-12V-DC...MkWBZJdrTnt8Mw

https://robotbits.com/robot-parts/mo...cket-pair.html

Word of warning...DO NOT USE THE STANDARD GRUB SCREWS!!
Go to Maplin and buy a £10 assortment box of M3 and M4 screws that you can tighten properly. Then screw your motors to the brackets, wheels to the hubs, hub/wheel tightened onto shaft then tie wrap the whole lot down to your base plate. This is a crude way of doing it, but it's quick n easy and got me nearly to the final of the UK Champs. See below my weird robot, specifically the motors. You will need to solder wires onto the terminals.