MAN is a bit of a lottery. From my own experience, early morning arrivals seem to be ok when it comes to immigration (passport control) and customs. And then sometimes the lines can be horrendous.

Personally, I hate Manchester Airport, all 3 terminals, with a passion so I tend to stay clear. The airport owners are trying to maximize retail space, so much so that the airport terminal are more like shopping malls these days. Even the arrivals hall (especially terminal 1) is shocking.