Hi @Paulma
You would need to get Extrabox added to your subscriptions, this will allow you to use 2 set top boxes.
Please see below article for info.
http://bt.custhelp.com/app/answers/detail/a_id/48891/~/extra-box-with-bt-tv-on-the-go.
If you require any other info please drop me a PM and I will do what I can to help.