So in the end i went with a take on a minories layout.
Ive kept the 3 platforms and added some points to give a run around in platforms 1 and 2. Typical train size is likely to be a 2 or 3 Mk1 BG parcel coaches and couple of mk1s or mk1 suburbans - not sure which would be better.
DMUs will also feature. Loco hauled trains will be hauled by class 20, 24, 25,, maybe a 37 and 47.
Managed to fit in a siding for the station pilot - currently the orange 08.
Also managed to fit a siding with a goods shed to introduce some goods traffic.
Fiddle yard is 4 track.
Total length of the layout inc fiddleyard is 9ft.