I lived in Wandsworth for 42 years and I only left in 2018. So I can only speak up until then. I had my fair share of battles over the years but my experience always was that once you got to someone more senior that 'common sense, logic and reason' kicked in and you could sort problems out. I found it quite fair in that way and I didn't have to go to tribunal as most things you could sort out without needing to.
While I lived there I moaned about it a lot but now I've moved away and now live in the Fires of SEND hell I realise that actually it wasn't really that bad. Or maybe absence makes the heart grow fonder! What I will say is that there are some really GOOD quality specialist schools in Wandsworth and there's quite a few of them. I think their transport policy is something that should be rolled out nationally to be honest (assuming it's not changed since 2018).
Again like anywhere EHCPs can be a bit non specific and that's not great. I think their actual procedure for EHC assessments is a really good inclusive co-productive one but it's not always actually followed. If it was followed it would be REALLY good. Nothing's perfect of course. My kids were all late to be diagnosed by the NHS and hopefully that has now improved because that caused a lot of pain and agony for all of us. The Consultants covering Autistic and ADHD I think are REALLY good (when you do finally get to see one).
In terms of professionals there are some real gems and some I can't remember what their names were.
That's about the size of it really. On the whole not too bad (but only saying that because I've now seen MUCH worse).