You are mid career, so academic cert not much use unless in govt sector.

The important thing is what was your exp in Navy & security? Do you have anything to sell to employers that your skills are relevant?

For BP you should have exp in things like manpower budget planning, employee engagement tracking & strategy, some work on succession planning, ability to debate with senior management, ability to communicate difficult policies to junior levels.

For C&B you should be very fluent with statistics, market research and strong financial knowledge, can do cost modeling & projections. Ability to present business case & engage senior management in discussion is highly sought after.

If not the only other way is to start from scratch, but you could be disadvantaged because of your age & pay. Alternative is to go into generalist/admin role, but then prospects are not as good compared to Navy.