Cruelly, English does not use "half to nine" the same way as it does "quarter to nine." It will have to be "eight thirty." And -- perhaps a British Duolinguista can chime in -- I think that "half eight" would also be a valid translation?
Just for interests sake, I think half-to-nine is not widely used anymore, but was pretty common in the recent past. I might be wrong..
I haven't seen it in American or British films of the twentieth century. Could you be thinking of somewhere else, maybe Ireland or India?
I would also say "I sleep at half eight". The word past is unnecessary
It depends on what part of the world you're from. "Half eight" is rare in Australia, "Half past eight" is more common, though I think most people I know would just use "8:30" most of the time.