I don't mean to be negative, my comments are meant to be realistic and practical - not often what someone who is following a dream wishes to hear. Given that you have 1-2 years(?) in college, then BRNC and afterwards flying training then we are looking at career appointments for you several years downstream.
I would suggest that for now you sit on your hands with regard to thinking about choices post BRNC, and wait for the results of the SDR, and general government spending review. We are not talking a long time here, the results should be announced in broad brush in about 2 weeks, and in finer detail over the next few months.
Somewhere in all the detail of government spending should be the decision whether or not to privatise SAR. You will also get an idea of how many FJ the RN will have in years to come at the same time.
In the meantime, keep working on those UCAS points.....