Not sure where you got that advice but I can't recommend it. I get really bad prickly heat - and I don't tan. Someone suggested a few sessions on the sunbed before going on holiday would help get my skin ready - and I just ended up with really bad prickly heat; even worse than I usually get in summer. Maybe it will be different for you, but I'd be very very careful. One of the triggers of prickly heat is sweating, which you do when you go on a sunbed - the sweat glands get blocked and the skin can't cool down properly. I find the only thing that keeps it at bay is antihistamines, staying as cool as possible and covering up in the sun. Not fun, but better than turning into an itchy beetroot.