I finally sorted out installing Gallery 2. Was pretty easy actually. A couple of files didn’t uploaded properly but that wasn’t a problem.
All I did download the latest typical install, extract it locally then upload all 18 Mb of it. Created a new MySQL database for it (Siteground provides CPanel / phpMyAdmin access). Followed the guide for tweaking security settings. Ran the installer and then uploaded some photos and jobs a good ‘un.
I’m not much of a photographer so most likely it’ll all be of the cats! But it’s a start.