The B decision is well documented. We know that there was a glimmer of a C variant once.....but we didn't have the money to make it stick. The B will be the only variant UK will put to sea so we just have to get on with it.
The point of mentioning the RAS thing is the logistics trail isn't small for that either. It has to follow the CAG as you mentioned, therefore it must be protected which all comes at a cost. Losing the stores ship to an enemy torpedo would have serious knock on effects. A combination of land and air delivery to a land base spreads your risk somewhat. It's swings and roundabouts and we have invested a lot in DOB infra since 2005.
As I said, I think Carrier Strike will be a potent enabler for political choice and is worth the price tag.