Ghostie,
You will not spend 8 months at sea flying fast jets with the RN!
Joint Force Harrier will be 50% manned (ie 2 RN and 2 RAF Sqns) but hosted by the RAF. The SHAR will have left Service before the GR7/9 Sqns stand up in their RN guise. Whilst the RN Sqns will take the lead in embarked flying the RAF Sqns will also go to sea. When JSF and the CVF come along all Sqns will go to sea, indeed if JSF moves right much then all GR7/9 Sqns will be required in CVF.