What size crochet hook do i need?

You will need 4.5 or 5

The buttons are fixed and elastic loops need to be streched over them which with long nails can be very fiddly.

like this

It depends on how big the loops are but a size 4 would be perfectly manageable and unlikely to be too big.

Excellent, thank you ?

The first thing that came to my head was ...'for loom bands?' What has my life come to! x

We forgot this on the day... my mum had to use a hair grip!! x

Ha ha my neice is obsessed with loom bands!

Fingers crossed i remember the crochet hook on the day, if not at least i know hair grips work ?