Have you been sent an email with the forum link that looks something like
https://ndsa.uk/forum/conversations/YOURNAME-and-NAME
If you click on this link in the email this takes you to the forum page specifically set up for you to arrange sessions with your mentor
(whose first name should be the second on the link)
It will should list "4 Participants" That is you and your mentor plus two admin staff.
If you, your mentor or admin put a message there it should send an email message too.
Hope this is helpful and makes sense