Saw this pop up on the new posts and thought I'd chime in.
I've not had Indian in the UK, but have dined at Sanaa and was unimpressed. It is not that flavorful, and definitely not hot.
If you want true Indian (at a restaurant frequented by Indian families) then head to Memories of India on Turkey Lake Rd. just north of the Sand Lake Rd. Turkey Lake Rd. intersection (K Mart is in the same parking lot). It's true authentic and you'd better really like spicy if you say so!
Hope that helps a bit!