advice please

[carla]

I am going to be looking after a Polish boy in April. His mum is having a baby in October, and she wants to give him a break when she goes on mat leave for 2 months. she says after that she wants him to come back to me. How much should I charge her a week to keep his place open? this hasn't been discussed before either, she has just emailed me.

[Pipsqueak]

a retainer is normally half the normal fees ie normal costs are £100 pw therefore a retainer of £50pw is taken