I guess Bourne will be a bit of a drive. It is run down to be fair and no cafe. I think the school is fine though. It will be very quiet compared with panshanger (or anywhere else for that matter!!) but its clear of controlled airspace and you can do lovely and quite easy nav trips up to the norfolk coast, then down say southwold. This will build your confidence/skill level whilst being a pleasant way to spend a few hours.
There is also an extra 200 to rent there if you ever fancy finding out what serious aerobatics are like!
I would think though that Elstree makes the most sense.