Thanks very much for the welcome and the advice, Carlton.
I do have the manual for the Porta mount. The SCT has its own mount - I’m not sure what it is but it’s timber and there could be a bit of a hand made element to it (Dad made some of his own parts and mounts).
I’ve no experience as a stargazer so I’m learning that bit too. I’ve got a planisphere and a YouTube subscription to CrashCourse Astronomy so that’s been a start
Thanks very much for the docs you attached as well.
I’ll definitely draw on the expertise of the forum when I get stuck.