Generally the more you pay for your gi the better material and quality you will get. As children grow quickly a single weave value gi (£20-£30) will suffice. Ensure you get larger size to allow growth and shrinkage.
The club can get discounts from many of the UK distributors, this will benefit you and the club. So please don’t hesitate to ask.
Have a look at a variety of IJF approved suppliers:
British Judo Association Store
Adidas (DE) via UK distributor CIMAC
DaeDo International (ES) direct from Spain
Essimo (NL) via UK distributor Ultimat Defence Limited
Danrho (DE) via UK distributor Kwon
Kappa (IT) via UK distributor AVA Sports
Matsuru (NL) via UK distributor