dave smith:
So it's more like a £3.20 voucher.. still pretty good though
Well, £3.20 and then £3.10 voucher
Spend £3.70, save £10 - plus there are invariably unexpected (or unannouched) money off tokens so can be a little more worthwhile.
I try either buy mine from Tesco/Sainsbury to add up the loyalty points (so approx 30p value in Tesco Clubcard Deals) or from Superdrug's where I get 2.5% cashback on offline shopping via Greasy (so this would be 10p cashback - if I can get to S'Drugs both days)