Welcome to Flyertalk and welcome to the BA forum axionpv2, it's good to see you, and I hope you will continue to be active here.
The TCP process for Gold cardholders is exactly as you have described, it's essentially a manual process to get the seats selected. With Theoretical Seating in place (see Dashboard) then it's probably best done this way or your companions will be blocked off from sitting near you at T-72 hours.