It certainly is an interesting company (I've applied to it for my Year in Industry Marine & Tech div, along with several other companies), it seems to have a hand in defence but still have strong civilian components which can only benefit the naval sector and vice versa like communications, nuclear, development training + management support.
It is a lot, when you look at the RFA roster we're actually increasing our tanker force from 5 to 6 for a period until the Wave's go when it'll be 4.
But when you start counting off what the RFA tankers do then they're actually quite scarce, the fact that the RFTG technically should have a tanker assigned to it but deployed to the Med without (same with the T45s) shows something. More often than not they're being tasked with counter piracy + narcotics patrols.
With respect to the RFTG in the Med, it should have a T45 + RFA support, it's supposed to do what it says on the tin so when it goes to sea without 2 key assets; support + AWD to me it's not yet ready, not to mention that any experience T45 crews get with big carriers can only make CVF integration with the RN that bit easier.
EDIT: Also IIRC MARS is an umbrella term and will also encompass the MARS SSS when they arrive which should be fairly soon for Austin + Rosalie, so gotta start calling them Tide class fleet tankers now