Cabair doesn't promote a social 'scene', but I recall that Jill's cafe (restaurant!) always offered good food and drink, and I have met many interesting characters there. The Aero Club was a little divorced from the flying training side of things, but I'm sure the welcome is warm.
Regarding learning to fly at Elstree, the runway is challenging, the airspace demanding, the traffic busy, and for all these reasons, if you can go solo at Elstree, you're on the right tracks....
Watch out for light winds and runway 08 (the slope will catch you out) and always land in the right place and at the right speed (this advice holds as true for a C150 at EGTR as it does for a B777 at EHAM).
I did a lot of very rewarding and happy flying and instructing at Elstree, last visiting a couple of years ago. From a personal perspective, I hope you choose Cabair, and I hope you learn at Elstree. The training will stand you in good stead. Study hard, make sure you understand what you are doing and why (ask your instructor if not), and enjoy!