half past

2+2=0 (mod 4)

"Half eight" is just a shortened way of saying "half past eight" in England.
In England "half eight" means 08:30 or 20:30. If people in England want to say 4:00 they'll say "four" or "four o'clock" (not "half eight" or "quarter sixteen"...).

As for pints, I've never seen a 1.5 pint glass. You'll get a pint glass full and a half pint glass full. If you ask for a half pint you'll get a small glass.