Instructions:At Checkout you can use code "15GRM" to get 15% Discount on all purchases. I think you can use it in conjunction with Quidco cashback of 5.5%
There are other codes as well which you can't use with cashback sites.
All below codes are only Valid fo January 2017.
GETFD (Free Delivery).
GET10off (10% Off)
15off50 (15% OFF ORDERS OVER £50)