Hi
I am not sure what the going rate is for host families but I am presuming it would be less than boarding at the school. Might be worth talking to Tring Park about what age Dc's can be with a host family.
Hi my DD is going to Elmhurst in September so we have a spare room he is currently at Tring Park Associates and goes to school in Tring. We live in Tring 10 minutes away, are you looking for somewhere for your DD?