School bag

Definitely don't take Smiggle.
Safest bet is to take plain stationery (supermarket own brand, Staedtler, BIC etc)

It's hard to advise on bags as different schools have different fads. My children all take backpacks as they walk to school and often have pe kits as well but some girls carry totes. Is her y6 bag neutral enough for y7? If so I'd use her y6 bag then buy one once she sees what other people have.

I agree to go with the flow and see what's in. Again- would normally say "strike out with your own style" but that is not fair to kids. Having had parents who did this and having suffered the consequences (and this was late 70s!).
When my dd has her transition days, i suggested she took a sneaky peek at what others had. She saw loads of girls in Kickers shoes so we are going for them.
As for bag, probably Adidas - she has one now.

Agree it may be better to wait - also to see how much stuff she will need to cart around. By Y 9 ds had huge 35 liter backpacks because of the amount of stuff he needed to carry. But if they have lockers, they wont need something that big.

Last week I'd have said hang out at school kicking out time and see what they're carrying. Too late now. My DSs have always had a rucksack, OGIO last time, but schools do differ. At one local school the trendy girls all have oversized handbags, Cath Kidston etc but they're not good for your back.

Most important would be not too 'young' looking. Maybe start out with something cheap and let her trade up once she has seen what's 'in.'

My ds had a slazenger backpack in year 7, Adidas for year 8 that I imagine he's keeping for year 9. Some girls have huge shoulder bags, some have backpacks. There's not an 'in' bag at his school

It deoend on the school tbh. My dd has a kipling backpack. Some kids have shoulder bags. Ds just has an Adidas backpack

I don't usually advocate following the crowd, but i totally understand why you want to help her not stick out like a sore thumb.

I think it is impossible to say what will be in vogue where you are, it depends on where you are in the country, what the local trends are. I would doubt Smiggle is in though, is much more of a junior school trend round here.

Why not use a bag you already have for the first few days, then buy one once she has sussed out what would fit in and also be useful? It is likely she will have a lot of stuff to carry, especially if PE and food tech are on the same day.

I can pretty much guarantee that wherever you are in the country, Smiggle is hot with primary children only.

Superdry and Hype rucksacks are popular here. Stationery seems to be a huge mix- but mainly WHSmiths, paperchase, supermarkets etc.