Amazon . . . yup, I get my Canon paper for about 1/2 price and "FREE Super Saver Shipping". The pricing fluctuates; so watch it and you'll save biiiiiig time. Same deal with the Canon OEM inks; I pay from 1/3 to 1/2 the retail price.
Repeat: the prices fluctuate, so monitor them and pounce when the price is right. Stock up a bit.
I reside in the U.S. so I don't know about UK pricing on Amazon. Please check it out; the pricing I get there makes Canon inks absolutely affordable!!