I've been having a great run with Co-op lately.
About once a week, I either forget to take my packed lunch to work or can't be bothered making one the night before, so I go to the local Co-op for lunch.
I go for the meal deal, sandwich, snack and drink for £3.25.
I'm a part-time student, so I swipe my NUS card for a 10% discount*, down to £2.92. Not a terrible price in itself.
Then every week, the checkout spits out between £1.50 and £2.50 of vouchers.
I always get a 50p off when you spend £4 and the other is either £1 or £2 off a specific category (eg fruit & veg, or meat and poultry) with no minimum.
So I tend to go to a different branch, one near home that I know does a lot of reductions to spend them.
The other week I had a £2 off meat and poultry and a £1 off the "loved by us" range, found a few packs of chicken breasts from the loved by us range marked down from about £10 total to £4 total.
Went to the checkout:
everything rung through, total: £4.00
Loyalty card swiped (did this first to get £4 worth of points)
50p off £4 voucher, total: £3.50
10% student discount, total: £3.15
£2 off poultry, total: £1.15
£1 off loved by us, total £0.15
Checkout girl looked a little confused, but still gave me the 5p change from my 20p coin... and a 50p off £4 voucher.
That's the best one I've had, but I'm regularly getting big piles of stuff for very little money this way.
* The NUS discount works on everything at Co-op, even reduced items.