The TPO is apparently expected back in service in 2025, according to that Main Line magazine article. Announcements will surely be made when it happens!
The Autumn Gala this coming weekend (Thursday to Sunday) should have something like 6 steam and a diesel loco, with 3 passenger trains plus a DMU, 2 freight trains (vans + tanks). These will run about 26 return journeys daily (inc freight). So about 3 trains each way per hour average in daytime, and as much operational interest as it can fit in.
I am certainly looking forward to it.
[edited for clarity]