Warspite, or failing that the Vanguard, if the navy don't save Illustrious I'll be pissed. Maybe the previous Ark Royal as well, though she was getting a bit knackered by the time she was scrapped, also if she was still in being in 1982 it might have given Argentina second thoughts (even if she could not have been put back in working order before the war was over).
Also examples of the Type 42, and Type 22 and 23 Frigate (though the last two are still in service), we suck at keeping hold of our maritime history in this country. It almost seems as if we say, hey we got the Victory what else do we need?
In terms of civvie ships the Queen Elizabeth (1), Olympic if only as a memorial to her lost sisters, and we really need to see about getting the QE2 back before it ends up on the bottom of Dubai harbour (or a chinese scrapyard

)
Further afield, obviously the CV-6 Enterprise, one of the WWII Japanese battleships, and while I know they only just left service I hope Russia saves one of the Typhoon class subs, they're just so cool. CV-65 would be nice but the reactor problem was never solvable.
Oh and in a slightly off topic example, the original model of the Enterprise (NCC-1701) deserves better than sitting in the back of a museum gift shop.