@peregrit You could perhaps call Admissions (on Monday) and ask to speak to them about the assessment process this year? I don’t think any other parent will be able to reassure you, because it has been so different. Though, fwiw, given the other offers your dd has, I would assume she’s more than capable.
In terms of uniform and equipment, if you can (covid permitting) go to the MIV tea in the summer term and head straight for the second hand stall. Get the sports kit (lacrosse stick, goggles, any sports kit that’s left in the right size) there, then top up with new where you have to. There’s a list somewhere on the school website of the ‘must get from approved supplier’ uniform items, stick to those, at least to start with. Dd has £10 trainers and football boots from Sports Direct to leave at school, but she’s not at all sporty so she doesn’t need proper lacrosse boots or anything. I think she could have got away without some of the ‘must have’ uniform items (they’re really not strict about it, and they can mix and match what they wear according to their preferences) but your dd might not want to take that risk. Definitely don’t bother with the uniform swimming costume, any black costume will do (Asda does a very cheap one that looks nearly identical to the official one).
Apart from sports kit, we didn’t buy anything in particular, though as the first term went on there were a few bits and pieces. Things like folders to keep homework in, the calculator the school wanted them all to have, a warm hoodie for commuting in as she was finding her coat too thick.