I've noticed LHR ATC seems to still pack in a fairly tight approach pattern these days although there does tend to be less stacking. There are of course still going to be pinch points. In terms of approach line ups it's entirety possible that fast exits and runway vacations are called for to prevent other aircraft behind having to perform a go-around. It's always fun in those situations catching unsecured belongings from passengers sat further behind as they slip off seats and down towards the row 1 bulkhead - I'd have about 20 iPads and pairs of glasses now if I hadn't stopped them with my size 11's and passed them back over the seats to their concerned owners!