A very modern fleet but one Bay is used as Mother ship for a minesweeper flotilla in the Gulf so no disponible out and one Albion is not active in reserve, can be disponible quickly eventualy ?
There's a difference between how long it takes to reactivate a ship in peacetime and how long in wartime. In 1982 we had a similar position with our LPDs, one active (Fearless) and one in reserve (Intrepid). Peacetime estimates were that it would take 6-9 months refitting to recommission and another three to six months to work up the ship and crew to be ready to deploy. Intrepid was recommissioned and sailed for the South Atlantic in just two weeks. Where there is a will, there is a way.
Amphibious operations are rarely done at the drop of a hat, there would be plenty of warning to the Navy that resources would be required, and during the detailed planning stage if it was determined both LPDs were needed, the recommissioning process would be expedited. Similarly the Bay class in the Gulf would be reassigned if necessary, another, less important ship (even a chartered merchant vessel) could be temporarily allocated to the MCMV support role. The Bay that is assigned there at the moment is only there effectively to give her something to do, for which she is reasonably well suited. An Amphibious operation would have first call on such assets in wartime though.