There is a gap at the bottom of my front door (handle side) and the door does not shut unless it is locked. Can someone offer any advice on how to adjust it properly. I have tried adjusting the hinges but am not too sure whether I am adjusting it properly as it doesnt seem to help.
You say "the door does not shut unless it is locked". The trouble is that most upvc doors do not pull tight to the frame until the handle is lifted, its inherant in their design.
If the gap is on the handle side of the door then adjusting the hinges probably won't help.
You could try adjusting the centre latch keep so that when the door latches it is tighter to the frame.