I have school uniform sorted, it't the out of school clothes we have in abundance and causing me issues.
FYI, before dd started school a friend advised me to get a set of clothes for each day for school. I'm glad she did, she said it would depend if they would change out of school clotehs after school but that her dd (18 months older than my dd) 90% of the time came out of school with something down her skirt/t-shirt and it made more sense to leave her in school clothes rather than dirty 2 sets of clothes, and have enough for an outfit per day with no washing.
I took her advice and actually dd is a fairly clean child so it may not have been necessary, but the uniform doesn't cost much these days, esp if you buy when it's 3 for 2 and get the packs of t-shirts with 3 in a pack.
This year I bought dd shirts instead of t-shirts and I bought 3 (3 for 2) so she will have to wear them more than once or i'll need to wash during the week, but I think she will be able to make them last a week most of the time.
DS on the other hand is messier, but someone handed down their ds' clothes and I haven't bought extra (although I may if need be during the year!) so school clothes wise he has 5 t-shirts, 2 jumpers and 3 trousers. I bought 10 pairs of socks
they were in packs of 5 for £3.50 and I just know they'll go missing 
As for things like coats etc, they seem to have about 5 coats each
I sorted the shoe/coat cupboard and was
as I hadn't realised how many they had, they now have about 3 each - 2 winter ones and a raincoat. I may as well keep 2 coats each as they are there, but wouldn't go out and buy 2 IYSWIM.
Thanks for all the ideas ladies.
I haven't done dd's wardrobe yet but ds' is so much better since I cleared out loads of things, I can put it all away and not have to cram it all in
DD back at school tomorrow so I may attack her's then, if not tuesday.