I have flow with Ivan at
Flight Training London. He used to work at Panshanger as an instructor and I can vouch for his teaching style and expertise.
Does anyone have any knowledge of Henlow?
Henlow is also good. I have flown with Paul Tribble who was ex-Panshanger. The good thing with Henlow is 3 x runways, so less crosswind issues to deal with. The negative is RAF security, which is fine for you, but means a few extra steps to bring in family and friends - though not a major hassle.
Fowlmere is great, I have flown in and out of there to visit an old friend. They use Archer III's for training and I have heard the instruction is top notch.
Conclusion - there are lots of places, and a lot will have an ex-Panshanger instructor somewhere. Finishing your PPL depends on location and whether you get on with the people and planes at said places.