AIB will obviously give you good experience. My daughter did both. The essential difference is the AIB water is wet and cold. The RAF water is warmer and dry. Also, when you have constructed a piece of apparatus you all take time out while health and safety kick in.
Now why did you wash out at AIB? Be honest. As a graduate with a decent degree, not underwater basket weaving, they will suspect you are overqualified as NCA. Maybe you are looking for the easy option; glamourous life and no responsibility.
A poncho and no food for 3 days on Otterburn would soon disabuse you of that.
No you would have to come up with a cracking reason why you would be gods gift to airborne electronics. You have an abiding interest in radar theeory, prf, arp etc and know all there is to know about electronic warfare; ditto anti-submarine warfare and maritime ops.
Ordinary sods with the minimum qualifications are different. The system expects them to know didly squat and will teach them.