The Lambourne 1Z RNAV procedure pretty well follows how you'd be vectored on a normal day. The trial is simply an experiment to satisfy ATC that pilots can keep within the narrow track, height and speed parameters in preparation for an "Estuary Arrival" which is your 12-15 mile straight in for 27.
The LAM1Z will probably be never implemented "for real", LHR is just too busy for that other than at 5am.