The vast majority of landings are manual so you can pretty much answer the question yourself. Autolands (AP and A/T left in) are generally only performed in low visibility conditions or when the crew are required to undertake them for currency reasons or training.
When you turn the "automatics" off is really down to company policy and personal preference. In a busy place like LHR you might leave them in a bit longer and let the autopilot establish the aircraft on the localiser and glideslope and let the A/T take care of the speed control that ATC will require until 4 miles out. Thereafter it will more than likely be turned off. At quiet airports the crews might well elect to disconnect earlier or even take a visual approach and self position.