have you got pd sta that you can discuss issues with at the lea? i would be tempted to put the risk assessment for the electric wc in writing and ask for it to be done prior to the surgery, so that everything is in place for when dd returns to school (and copy it to the chair of governors and the sn governor) as well as the senco, ht, and class teacher. (after your meeting!!!)
we've had a few issues where the 1-1 has been overly helpful, but it's usually fairly easily nipped in the bud by reminding the school that the 1-1 is there to facilitate independence, not take over and do everything. it's tricky - your school have obviously gone the other way!
can she type? dd2 struggles with writing and in the very early years it was easier for school to scribe (i had a similar issue myself as i did a stint supporting a gcse student) but we are currently transitionsing to ft keyboard. obv when she really can't manage, then the 1-1 can scribe, but dd2 finds typing much less traumatic than writing. (she has athetoid cp - sometimes her writing is neat but slow, and other days she can barely get the pencil on the paper! sooo variable.)
mm, playtime. is she statemented? what does it say about support - does she have lunch cover in the statement? there's no real reason why the supervising staff shouldn't go all over with dd - is it just convenient that she stays put? is it not possible for the staff member to take her outside briefly (well wrapped) for a circuit, and then tootle about indoors/ library or wherever? bit harsh that she's imprisoned! id she hasn't got any lunch cover then i can sort of see why they are going for the easy option.
i'd go in and be lovely and smiley with the ht. it's a new ht, new teacher, and you all want the best for dd! (emphasise this a lot with a huge smile!) and just raise your concerns in a non threatening way. obviously you want dd to be treated as far as possible as the rest of the kids, but suitable accomodations made. ask them for their advice. a lot. bow to their superior professional wisdom. a good bit of flattery this early in the relationship can smooth the way for years to come.
and then you can be a proper pita later - but get the foundations built first.
is the ot coming into school? our ot and physio used to come in once a term and were really good with specific advice for 1-1s. you need a good one though...