knut 75, welcome to this forum
Some answers to your questions;
The amphibious fleet consists of two Commando Carriers and three Fearless Class, in reality one would Fearless would probably be in refit at any one time. There may have been 3 Fearless planned in real-life and I thought, why not make a lengthened version just for fun!
The gun armament is one of Bill's ideas, basically the RN follows other navies of the time and begin to develop a series of automatic twin Bofors L/70 mounts. This is before Sea Cat, so in AU world Fearless would have been planned with an all-gun armament but two Sea Cat were added before completion, Intrepid had four Sea Cat as historical except for the addition of MRS-3 to give a better director capability over the forward arc at least. The second Mark of the AA twin is a GRP variant which is unmanned and lighter and equal to the Breda twin. I added two of these mounts to the third vessel as I think more gunpower would have been more useful for close-in and crossing targets than the reletively slow and inaccurate Sea Cat (which gain all-round MRS-3). I think in a Falklands scenario these ships might have performed slightly better at AA self-defence.
The Westminster is pure fantasy for us, but Rotodyne is too big for effective shipboard operation and Wessex is good but the thought of a mid-50s idea to disembark 40 troops and/or vehicles onto an enemy shore was just too much to ignore. As related elsewhere on this thread the Westminster was tactically too big and didn't last too long in this role.
Another point I'd like to add is that operating Harrier from the bigger third ship is also pure what-if fun. As far as I know it was never tried on Fearless or Intrepid in real-life but a bigger deck might have made it possible.
On hovercraft, I like the green camo but I agree grey is more likely (unless they are operated by the RAF!!!) and we have some minesweeper plans for the hovercraft too!