Fair bit of background required...
DSD (one of 3 DCs who live with DH's exW) has always struggled with school. She never took to reading, unlike her twin, and generally found things difficult. She's had a few tests through the school for dyslexia but nothing conclusive.
Yr6 was just awful due to the SATs, but in yr7 at a new school she really seemed to settle. Still struggling academically, but happy. However in yr8 she started getting migraines and has missed loads. She is constantly ill and exhausted, and now the school health officer is getting involved.
So today exW forced DD to go back to school, DSD was crying. In the end she said "I want to be homeschooled by dad and wobbly" 
I'm amazed she said it - and she really means it. We've mentioned homeschooling in general but she's obviously latched onto the idea. ExW is not keen, due to the usual worries - socialising, exams etc... Fair enough. We genuinely feel that DSD would do well with HEing... school just isn't right for her, she's clever but not in an academic way. TBH we've always dreamed of HEing her especially as the school is rubbish! Work not marked, cancelled lessons, disruptive pupils not dealt with etc... and DH said today that we can do it (he's off work for the foreseeable future due to injury and I'm looking for PT work)
So... ExW will take some convincing. DH suggested flexischooling and she's interested - maybe that'd be a good compromise? Either afternoons only, or certain lessons. I know though that the school don't have to oblige do they.
Right, to the point then (finally!) - exW is going to arrange a meeting for her and DH to discuss DSD's future at the school. I am basically wondering what DH should say and ask. I have heard that some schools try to dissuade parents from deregistering etc so DH needs to know exactly what their rights are IYSWIM (we are in England btw)
Any help would be gratefully received :)