RN Flying Training
It is true that RN helicopter pilots can switch to FJ later on. It's not impossible for our RAF colleagues to do the same, but certainly less likely.
There are 3 occasions when RN pilots can be selected for FJ training:
1. Upon completion of DEFTS (RAF Barkston Heath)
2. Upon completion of DHFS (RAF Shawbury)
3. After you've flown helos for a few years and are deemed worthy enough
Any further questions please ask. Hope this helps!