Dyslexia Dyscalculia secondary

[OV54]

Looking for a secondary school for our daughter.
Diagnosis Dyslexia/Dyscalculia, block to learning is both psychological and cognitive.
We're in north London, all state secondaries have stated that they are unable to meet her needs (she has a band D EHCP).
All professionals involved state she needs a small nurturing environment.
Been recommended Mount House, daughter loved the calm environment, but they have refused 'cos daughter 2-3 years behind and they do not have specialist teachers and would not be able to differentiate the lessons enough for her.
Abingdon House, can more than meet needs, but we feel she needs something in between the "specialist" school and mainstream...any suggestions?

Oh yes, all pros agree mainstreams too big and would completely overwhelm her, as a previously looked after child, she is hyper-vigilant and easily overwhelmed, much of her brain space is taken up with monitoring her environment, school is a massive challenge for her.

Are there any other non-selective mainstream independent schools nearby?

It’s a SS but what about Egerton Rothesay? Or one of the other Cavendish schools such as The Moat or Bredon - each SS has its own feel, and if I remember rightly I think The Moat at least offer a more MS curriculum than Abingdon.

Have approached ER, but they say they are fully subscribed for the next 3 years!
I know Abingdon have a sister school, which would probably be more appropriate, is that the Moat,? it's in Fulham.
But, we're attending an assessment day at Abingdon, so could speak to them about the logistics of getting to and from The Moat from Muswell Hill.
Bredon, is that in Worcestershire?

Both The Moat and Bredon are in the same group as Abingdon. Brendon is in Gloucestershire, whilst in wouldn’t be possible for a day place, they offer residential.