15% off Impact Whey Protein and free delivery in August at myprotein. This stuff comes highly recommended if you read around.
Prices range from £9.31 for 1kg to £29.71 for 5kg (£5.94/kg) for the unflavoured.
By comparison Holland and Barrett sell protein powder for £24.99/908g, although its usually on offer for £12.50 this still makes it £13.77/kg
My protein clam to be the cheapest in europe so if you find it cheaper, contact them and they'll match it.
PLUS - 5% off your first order with a referral code so could be up to 20% off. Don't think we are allowed to post them here but loads floating around the MP forums.
So get stocked up and i'll see you on muscle beach.