I was in my local Superdrug today to by some EDT.
I saw an offer on lots of posters and shelf-edge labels in the fragrances section saying that you can get a voucher for £5 off when you spend £30 or more on fragrances. These vouchers are in a little booklet on the desks (please ask if you don't see them).
The vouchers are valid, if I recall correctly until the end of July.
I used this voucher on my first purchase with any problems, but I was then given a 20% off voucher for my next purchase (I think the minimum spend was £15). So, I then returned to the store later, got ANOTHER £5 voucher and bought somemore fragrances, and managed to get £5 off, and then 20% off.
EDIT: Just checked my receipt, and although the sales assistant scanned in the £5 and THEN the 20% voucher, it's taken off 20% of the original price - winner!!
Hot or what?