I am assuming you guys never dated due to the fact that you say you were close during childhood but drifted apart and never spoke in secondary school (which is years 11-16 and then two more years until 18 if you wish to stay on). I feel like you are holding on to something that was never there, holding on to this version of him as a kid, he is most probably not that same person anymore. Besides you are only eighteen, you are still young, you are only just beginning your life, maybe you are scared to start the new chapter that awaits which is why you are trying to cling to the old one, maybe it's more comforting.
Either way, I suggest you should probably try and reconnect with him as friends, you seem to have romantic feelings for him but you have no idea whether he can reciprocate these so you can only really reach out to him as an old friend. His family members and close friends should be able to provide contact details for you, like an email address or something.
And sorry but dreams are rarely prophecies. You are only having these dreams which feature him as he is heavily on your mind.
[SIGPIC][/SIGPIC]
Love is like a merry-go-round: you get all dizzy, and then you feel sick!