It is part of the Great Britain X tour. It is 9 day tour, that goes all over the place, including Inverness, Kyle of Lochalsh, Fort William, Bristol, Penzance etc. It is listed here, through they don’t give times: http://www.railwaytouring.net/travel-tours/the-great-britain-tour
Usually you can figure it out from Realtimetrains, even if you don’t know the details. Probably best to check what it lists for TOC. It seems the steam locos will be operated by West Coast Railways, so it might be listed as WR. Or it might just be listed as ZZ, which is a generic/unknown code.
Maybe the times aren’t published on Realtimetrains yet. Worth checking again over the next couple of days, to see if it appears.