Additions Direct have some back to school offers on at the minute - click the link to have a browse, there may be a few bargains to be had! They have everything from footwear to underwear, at very reasonable prices.
But there's a bonus - there are lots of codes in the voucher section which you should be able to use - just check that they apply to you before you use them (E.g. existing or first time customer codes). So if you buy a number of items you need, you could get these at really low prices!
Good luck mummies and daddies!