Hi swifttroupe.
I am NOT trying to be a clever clogs but CDM 2015 is not supported by an ACOP but rather only by guidance, which in my opinion is unfortunate.
So, you will find the current guidance, L153 at the HSE website, but you might want to also look at what the ACOP and guidance that supported CDM 2007 had to say. You should be able to download L144 from the HSE Northern Ireland website unless HSENI have dropped it very recently.
In L144 HSE tried to address the excessive paperwork that was becoming the norm in supply chain "competency" assessments and included some good guidance on what might be appropriate and what would be disproportionate. Worked up to an extent to reduce the amount of bureaucracy.
In CDM 2015, the word competency was replaced by "skills, knowledge and experience" + if an organisation "organisational capability". You might think that this is essentially a longer way of saying "competent".
Problem is that no longer does L153 have the sort of helpful guidance that was contained in L144, so many H&S professionals in UK onshore construction are likely to spend quite a lot of time involved in competency assessments either to help get their own organisation across hurdles or to vet potential subbies.
Now, I have never worked offshore so I don't know quite how prevalent this is over there, but onshore lots of things have become assumed as LEGAL requirements when they are not. So the assumption that Contractor A or Subbie B MUST have RAMS.
Of course, this is a gross misrepresentation of what the Management and CDM Regulations actually requre but it might have become part of the mindset of those interviewing you and simply to explain that that your interviewers are legally incorrect might not be diplomatic!
However, my guess is that you probably don't need to fret to much about e.g. CDM and all the safety risks posed on an onshore construction site, as you should be able to draw on offshore experience to cope with almost all of them.
With the possible exceptions being transport both on and OFF site (i.e. logistics) which is a bit different to get things to oil rigs etc. AND the interface with the public. Very few people manage to climb onto offshore structures unless they are supposed to be there. In contrast lots of people want to walk alongside or get into onshore construction sites - obvious the reasons why, who does it and how often will vary depending on location and other factors. So, HSG151 would be good reading material. Possibly also this Guide to public safety on flood and coastal risk management sites - GOV.UK
But I was careful to restrict my comments to "safety risks". If you have a more forward thinking panel they might be quizzing you on occupational health risks which might be rather different to many of those which headline offshore. HSE is focusing on issues including some which should be up there offshore - noise, vibration, welding fume, but also on wood and silica dust which might be less of an issue on the rigs etc +, of course, the A word.
I have personally investigated 10 fatal accidents involving people falling when doing roofwork - I haven't a good estimate as to how many of their colleagues doing similar work would die prematurely due to exposure to asbestos but it will have been a much larger number.
All this said it's quite likely that much of the interview could veer towards mental health and wellbeing, and to "inclusion".
So they will probably want to hear what you have to say about e.g. mental health first aiders, Employee Assistance Programs and "initiatives" such as bowls of fruit in the break out areas and away days, but they might not want you to talk about what THEY could do to reduce the levels of work-related stress through poor procurement practices and working cultures, and, excuse the language, bog standard welfare facilities.
Good luck, Peter