Shoes, per year: 1 pair trainers, 1 pair walking boots, 1 pair summer shoes. 2 pairs school shoes.
Wellies I can usually get away with every other year by buying a bit big and using a liner.
Shoes average about £30 per pair, so £150 a year, another £7 for the wellies.
Some footwear can be handed down, but can't count on it.
Coats, I try to buy a bit big to get at least a couple of years out of them, I might manage 3 years.
One lightweight waterproof and 1 winter coat each. £30 a year if they can last 3 years.
Probably £200-£250 a year on out of school clothes.
I haven't had to buy any school uniform this year (bought big, and younger Dc has sibling's old uniform).
The year before I probably spent £200, including sports kit.
So say £100 a year on uniform.
So about £550 a year on elder Dc, much less on younger sibling though, due to all the hand-me downs.