I joind the RN a long time ago and have had a really good time. Flown Seakings, Wasps and Lynx and now just finished ATPLA ground exams and hope to get a job next year when I come out. I have seen many friends go through this and the I think it matters little if you have helo or fixed wing back ground. If you want it bad enough, you will succeed. It is true, however, that Virgin do like the Fast Jet boys and will actively recruit when it suits them. I also know some ex rotary boys with that airline.
If you want some excitement and colour go for the Navy. It is true that you are a Naval Officer first, but at the end of the day if you are a pilot then that is what you will do and "all the nice girls like a sailor" and the uniform doesn't harm. The Armed Forces will also give you a much broader perspective on life and enable you work alongside some real 'top drawer' people.
If the Navy offer you a job, I would take it and then look to the airlines later on. They will recognise your ability and experience and many of the chief pilots have a military background.
Good luck