You will often find the mix in butchers' shops, though I do not recall seeing it in supermarkets. The brand name in my part of the world is "Maykway", been around for ages.
I got some in our local chinese supermarket, hubbie said it was exactly the same as the takeaway. I've got a feeling I actually saw it in our local Tesco a few weeks ago.
If you ever get the chance, try a japanese curry. We have Japanese students who regularly make this and it's delish...especially if done in the slow cooker using caserole beef. It comes in blocks and you just add it to water or stock and it dissolves.