I hear eaurokids is the best my friends lo has had tv work as well as mamas and papas but after doing my own research they're not great as you have tp pay £170 for the shoot. They did accept Poppy but cause they would b/c they want our money

I do know littlewoods catalogue get their models from eurokids though as I asked them
So I got recommended to Elliott Brown and I've sent her photos off and just waiting to hear back now. They don't require any payment upfront.
There is a lot of waiting around and travelling, most shoots are in London and they require you be there for 9am (most shoots) so be prepared.
Your lo will be required to have a good temperament too not just a pretty face! Modelling isn't for everyone but I'm sure you know that