Most of the Maltese will speak English except for the elderly sometimes and people from what could be considered the 'countryside'. You'll find some of them will also just REFUSE to speak English even though they can
Maltese is a hard language to learn but I'm sure you're missus could tutor you lol

Expect to pay over the odds for cabfare and all that as well being British

Also, it get's very very very HOT over there and in wintertime the place floods lol
It is a very different culture that really takes getting used to if you live there although it will be easier now than when I moved there.