Hi, Joseph2541,
I've just moved the neighbouring carpark back to it's correct position after I found it mistakenly dragged on to Gloucester Road. 
I was also going to correct a few things here but thought I'd reach out first: the smallest parking area is actually a service road to the middle and SW (currently unmapped) car parks. The convention re. engratnances is for them to go on the buildings and to use barrier=entrance for a gap in the wall as it is here (although it's not common to use).
See the wiki on entrance=* for some guidance