Many many years ago when I was a humble technician, I went to do an atmospheric test on a furnace ladle pit at the steelworks where I worked. When I got there contractors were already in the pit cleaning it out regardless of the no test, no permit, no work rules. What made me smile was the guy wearing a martindale mask with a neat hole in the front where the roll up went. No one ever died from a dangerous atmosphere during my time there but we did have some scares and ambulances. When you work "job and done" it's amazing the risks some will take, they'd rather get to the pub early than risk their lives.
I do my safety passport at Alliance learning in horwich near Bolton, I *think* they do confined space training, though I’ve never done it there.
When I needed it (in a previous job) I used to get sent to Todomundo in Letchworth for some reason, our office was down that way but it didn’t make much sense to have me travel all that way, plus hotels etc just for a course ah well it wasn’t my money
Fleetwood Nautical Campus do Confined Space training, in Lancashire but maybe not the certification you need for ashore. Worth asking if it’s local to you.