If you are based at Welwyn, Panshanger is probably the best option. If you don't drive, I believe a cab would be the only wa
The comments I've read in the past about Panshanger are generally negative.
I am doing my PPL there, the atmosphere at the airfield is very relaxed, but the flying and teaching is taken seriously and quite professionally I can say.
The Piper fleet is kept and maintained well, and hourly training rates are pretty competitive. I've also had the same instructor since I started and all of them are very friendly and helpful. Herts_sc put it very well, the school feels like they truly have passion for flying as oppose to taking your credit card details.
The radio as mentioned is A/G, so don't always expect a reply straight away, 8/10 times you will get airfield info/radio check.
One minor dislike is during busy times the instructors seem to do a lot of multitasking at the reception which can delay you a bit.
The food is expensive, but very tasty. ( I believe you get discount with membership)
I am not saying Cabair is a bad training organization (CPL/ATPL courses seem excellent), but if you want to qualify for a PPL with out spending a lot more than needed, NLFS would probably be a better option.