There is an article in the JEC magazine, January 2021, on a successful repair to the interior mirror problem. It was resolved by spending a bit of time and effort to separate the existing mirror parts, make a template of the mirror glass and have a local glass company cut a new standard mirror piece to use in its place.
The correct Jaguar part replacement is unlikely to be available and when it was / is costs roughly £400 and second hand units are just as likely to fail in the same manner as your original. If you want to go hunting for an original replacement, get the correct part number from the Jaguar Classic parts website and run your search. The chap in the magazine article did just that, but ended up with a repair for just £10.50 and a few lessons learned.
For the leaking boot, check the seals around the periphery of the opening, especially at the top edges, could be a corrosion issue.
N6 JMX