Offshore work is a bit of a con as you have to pay £800 for Survival and MIST courses before your application will be accepted,
Then there are thousands of people applying for any of the roustabout jobs of which they are not willing take on anyone that does not have offshore experience.
Unless you have a trade or an engineering degree I wouldn't pay out for any of the courses in the hope of getting a job offshore.
Generally, to get a job offshore - as in rig crew - you have to be time served in a trade, or like you say an engineer of sorts.
To get a few trips in servicing over summer you can blag it a bit and take some short courses, as I have seen, but the opportunities are narrowing in that respect.
I actually have an engineering degree but don't particularly use it for what I do, however having it has undoubtedly opened doors for me.
The problem is that it is portrayed as being so easy as getting a job offshore, especially so by training providers (who are raking it in). A lot of people give up because they can't commit to 'getting a start' and have bills to pay in the meantime. But even so, you have to have something to offer, skills wise.
There always will be a requirement for good welders, electricians, pipefitters and mechanically minded people. One of my regrets was not doing Mechanical Engineering at university instead.