Question for a friend on student visa?

Hello all, I have a question.
My husband and I are moving in May to Cardiff, and our good friend and band mate wants to come. We told him hed best get a student visa then. So he has already applied to the school and is waiting for a response. No ucas needed, he is 24. So were wondering what to do. Were leaving in may and he needs to know what to do, come or stay until he knows if he got in? Can he come over on a visitors visa and then when he gets accepted get a student visa? He has already started the process, but now he needs to know if he can/should get plane tickets? We will be over in may and uni doesnt start till sept so thats a long time to have for them to process it all?
thanks for the advice hopefully,
Joni

Pretty sure a student visa requires an entry stamp to be activated. So he'd have to go back to the US, get the visa, and come in on it. Also, from someone who is now officially over her head in student debt thanks to international student fees, I'd suggest he stay there and earn as much money as physically possible between now and September.