Hi Mike
You only have to read the the archives on this forum to find the answer to your question .
At the end of the day your cv will sit on someones desk with a few other thousands all trying to get a foot into the rov industry .
Think of it as playing the lottery some do a course and within a short time there in however there are many others who paid out over 10k and are still looking after 2 years ,Just take your time and go through the archives on this web site and your see the debates that have gone on before .
So should you wish to spend a few thousand pounds on a nice certificate please do so , But will it help you find a rov job I don’t think so .Best you send off to all the main line Rov company’s your experience in electronics & Hydraulics and if they find your back ground is suitable your be put into one of there in house training programs . But there are thousands of trainees like your self some with courses and some without .
At the end of the day luck plays a big part , Your Cv could be the one out of all the other thousands .
Good Luck
Raptor