i know that ive said it before but if you can get a trade card for halfords then it is very worth while.
i went in the other day and purchased 1 litre of lm fluid £10.80 and two rear bulbs £2.49. with the trade card it was lm fluid £4.08 and two rear bulbs 0.48p you dont need to be einstein to work out the potential savings to be had!
this card applies to spares most fluids and tools and not luxury items etc however its always worth trying!
go into halfords and ask for one you never know until you ask!