Having seen the way QEC is coming together at Rosyth (and elsewhere), I think the ship will be operational as a helo carrier at the back end of the decade. If PoW is to be EMALS fitted in build (and why wouldn't you do it that way?), then I think she will be an operational ship very early in the 20s.
The unfathomable is the CAG. The definition of "operational" for the CAG will actually depend on what specific number of FE@R trained for deck ops has been specified as Full Operational Capability and more importantly, what level of funding is provided to generate the spares and training - buying the actual aircraft is obviously important, but only a part of the picture. The Apache suffered appalling press as it was being introduced, largely because the training and logs provision had been underfunded early in the programme and it was too late to correct the capacity problem. Hence stories about being unable to use the cabs and the whole programme being a disaster - I doubt anyone would use those words now. However, you would hope the lessons had been learned.
As for tankers, I'd go nowhere near F18. My personal preference would be to regenerate the low-time S3B that are sitting in AMARC in Arizona - a reverse of the Harrier sale if you like. The aircraft was configured as a tanker (both dedicated and buddy variants), could do reasonable ASW/MPA (although not with the full capability of a Nimrod), had a fantastic ISAR pod for a role not dissimilar to ASaC7 (though not AEW). A fleet of 20-25 (there are currently 60-plus frames there of S3B alone) and with a little creativity, you could have a core force able to do some (not all) of the LRMPA role, nav/observer training, CV-based tanking, CV-COD and CV-ASuW as well as some elint/intel capability.
The down side is that they will require funding against all the DLOD and more than likely a complete avionics refresh (nineties electronics and the 21st century are unhappy bedfellows) and experience with that is mostly bad (Chinook Mk3, SH2G etc). That said, they are available, should be cheap and with no CV-based "support" aircraft in production anywhere are the only option. The trick is to make sure that the capability / funding balance works.