Landing advice needed for newbie.......

I am using a Wilco A340 Airbus, I have read other threads and as a newcomer I have been trying to practice my manual landings... as it is easy to let the ILS do it all.
I began my approach and throttle back and deploy full flaps, at about 160 knots, so far so good. I disengage the autothrottle and autopilot and descend towards the runway, as I am about 500 feet above the runway the autothrottle cuts in and goes into full TOGA, I switch off the A/Throttle again but it won't let me slowly glide in....
I must be doing something wrong....and properly something simple...please can anyone offer any help...as I would like to perfect my manual landings.

Thanks