Picked up some Kinesiology Tape for £1.49 which is the cheapest I've found it.
It didn't seem to be on offer, so am guessing these are nationwide. Stocked with all the plasters and dodgy feet stuff.
I guess 5cm isn't the thickest but good for foot injuries, like mine.
Store locater: http://www.savers.co.uk/store-locator/
Kinesio Taping gives support and stability to your joints and muscles without affecting circulation and range of motion. It is also used for Preventive Maintenance, Edema, and to treat pain. Kinesio Taping is a technique based on the body's own natural healing process.
etc for more info.