I agree with Rive and LT. It seems weird and inappropriate for a T to suggest this, at least without consulting you at length first and having good reasons why such an approach would benefit you. I know therapy is different in different countries, but here it's very unusual for a therapist to meet family members, at least unless it's part of a specific approach that the therapist has trained in. It's also very unusual for a therapist to go to a client's house, although it has been done (my T came to mine once, but then she is quite unconventional).

I just hope you feel reassured that the reasons for your T to do this are solid and you have a right to your feelings about it, before and afterwards. You certainly have a right to keep any information confidential that you choose. Confidentiality is massive in the UK which is why speaking to anyone outside the therapy room (apart from a supervisor) is very, very rare.

I really help this works out well for you.