Just to add on the loco front
3) Then either buy an E4 or the preserved livery Adams from Hornby. You have a choice of E4 and you don't have to buy Birch Grove. I think the first Southern green one was a Bluebell livery at some stage.
Southern Green is the current livery of the E4 as seen in my picture below, taken on my trip there last month:
I got pictures of all the locos that were at Sheffield Park, let me know if there are any you would like a look at and I will post them.