talkmagic.co.uk

Anyone know an online store in the uk that sells hole punches the size of the circle on a bicycle card back ( about 28mm ) ?

Its a standard thing in craft shops..
Its used to cut holes in the front of greetings cards, and come in quite a range of sizes.
cards for magic also sell them. they are called long reach hole punches

http://www.cards4magic.co.uk/acatalog/Hole_Punches.html

Hobbycraft stores and Hobbycraft on-line do these, I use one to punch a hole in a playing card for one particular effect, it takes a bit of effort as the cards are quite resistant but you can get attachments for these punches to add extra leverage which helps. Being a skinflint I use an old engineering vice in the garage!