The Sainsbury's TTD product is made with Cheddar, regato and emmental and it's very tasty. I've never made it for myself so would be interested to know what other kinds of cheese would work well. I imagine anything that melts readily would be good, e.g. double Gloucester or gruyere. Perhaps a little blue cheese for piquancy?
Same for broccoli cheese, BTW. Thankyou.