...by becoming a free 'Quidco' member, if you aren't one already.
As well as their fairly well-known online shopping cashback scheme, they also have an 'in-store' scheme with several retailers, whereby you register your credit card number with them and then each time that card is used in that shop, it simply triggers a cashback payment to your quidco account. Not a very long list of retailers as yet, but it does include Cineworld, Halfords, Little Chef, Blockbuster and very recently, B&Q. As I spend a fair amount in B&Q that's very welcome news for me!
(FYI cashbacks are usually much higher for online purchases but you do need to remember to access the site through Quidco. They also deduct the first 5 GBP you earn each year as a fee (only if you earn it) - and that's very quickly made up.)
If anybody decides to sign up on the strength of this - suggest you use the following affiliate link, which will pay you 1.00 GBP (and me 1.50 GBP as a thank you!)(as opposed to 0 GBP for each of us if you go direct to the site instead):