Be aware that this may be a local deal as it doesn't appear on the website, but at the New Oscott branch there were shelves near the till full of protein and weight-gain powders plus a few pots of creatine and amino-acids all marked down to half price. Nothing special compared with online offers, but not very far off and might be worth a look if you can't wait for delivery:
Sci-MX GRS-5 Protein System all flavours 2.28kg £25
Sci-MX 100% Whey Protein all flavours 2.2kg £23
Maximuscle Cyclone 1.2Kg £20.99
Maximuscle Promax Diet 1.2kg £20.99
Maximuscle Promax Extreme Choc/Strawberry 908g £20.99
Maximuscle Promax Extreme Choc/Strawberry 545g £9.49
Can't remember the exact price of the rest, which was mostly Sci-Mx stuff, but most of what Tesco has online was on the shelf, except the larger 5kg tubs, plus one or two other things not available online and at half the web price.