Yes, it's Overclockers but you find a better deal. Personally, I've never had a problem with them, except most of their prices.
I've looked around and this is the cheapest that I've seen for three 4GB 1600MHz sticks of RAM. The only thing that comes close is 6x2GB RAM or 1333MHz.
For under £140 even excluding delivery this is a killer price; you can get 8GB for nearly as much as this. £143.09 including next-day delivery.
I haven't checked the price with the novatrise code, however.