OP, hi again, we have an option to buy the school book bag with the logo, but I hate it, and bought a different one which is bigger, has a strap to wear over their shoulder, and is a nicer colour.
Having tried sending ds1 to school with a rucksack last year, I found that his homework and letters were all getting holes in them and very crumpled up, it was useless - so this year he has a bookbag-shaped bag, which is 'fashionable' (like a laptop bag, pictures of boy stuff on it, skulls I think - eek) and will hopefully preserve his paperwork a bit more efficiently.
Honestly, bookbags are really your best option at this stage.
Everything else, pah, you'll be leaving soon by the sound of it so I wouldn't bother getting the posh stuff unless as I said you buy the minimum and sell it on when you go.
We didn't know what we were getting into, sadly - HT changed the uniform from generic, cheapo stuff you could buy anywhere to a posh logo and very restricted colours for everything else...even socks have to be a certain colour.
It drives me insane as we like the school (apart from her) and it's too late to move ds away from his friends, so we had to suck it up.