Sorry to Highjack your thread. I think I'm at the start of the same issue.
I got xbox game pass included with my fttp and added it yesterday via the email and content partner page as suggested. Everything worked as expected but I got an email soon after about the £10 charge? Is this normal?
Hi @redeye, welcome to the forum and I've moved your post to create your own thread so it won't cause confusion.
You should receive an email confirming you've signed up to the free offer and when your free subscription period ends. It sounds like you've just signed up to the standard Game Pass monthly subscription. You may want to opt out of this so it ends after the 1 month.
Please check that you've no other accounts linked to your BTID as these will cause an issue in trying to claim the free Game Pass. If you've old accounts linked to the BTID you can set up a new BTID for your active account at Create BT ID and as long as you use an email address that hasn't been used as a BTID before you should be able to claim the free Game Pass.