Instructions:Get £ 4 off a £ 40 spend on items in their May Mayhem promotion. Valid until midnight on Friday 20th May 2011.
Some quite good deals there such as the Pirates Of The Caribbean Trilogy and Bourne Collection on Blu Ray for £ 17.85 each and The X-Men Quadrilogy on Blu Ray for £ 16.85. Or Planet Earth for £ 14.85 if you prefer that type of thing.
This voucher may just be the sweetener that you need.