For some reason even though the offer is 5 for £5, you can order 6 for £2.64!! Thats what I've just done.
Website is: http://www.pixum.co.uk/
Voucher code is: 9eb6d-98cae-265dc
You have to add the 12inch posters to your basket then add the voucher code.
Also if you are a new customer, you also get 25 free 4 inch prints.
AND if you use quidco and are a new customer you get £6 cashback!!
So I just got 6 posters, 25 prints for £2.64
but as I've got £6 cashback, they'll have paid me £3.36 
Not sure what they'll be like, but got to be worth a shot
ETA: For some reason you can only use credit cards to pay, but Visa Debit & Electron seem to work as well, I used Visa Debit wooo
Website is: http://www.pixum.co.uk/
Voucher code is: 9eb6d-98cae-265dc
You have to add the 12inch posters to your basket then add the voucher code.
Also if you are a new customer, you also get 25 free 4 inch prints.
AND if you use quidco and are a new customer you get £6 cashback!!
So I just got 6 posters, 25 prints for £2.64
but as I've got £6 cashback, they'll have paid me £3.36 Not sure what they'll be like, but got to be worth a shot
ETA: For some reason you can only use credit cards to pay, but Visa Debit & Electron seem to work as well, I used Visa Debit wooo
