Hopefully Ireland will follow suit. It’s beginning to look likely.
Related question: has a law been passed anywhere that places gay couples under the same laws that govern heterosexual marriage, as opposed to a parallel set of laws?
Hooray for Britian, and welcome to the club! 
I believe that when same-sex marriage was legalised in Ontario, the wording of the law was essentially changed from “husband and wife” to “spouse and spouse”. I seem to recall reading that there was a delay while the forms were reprinted.
:: looks at Ontario government web pages ::
The form for applying for a marriage license says things like “applicant” and “joint applicant” and doesn’t mention the applicants’ gender at all.
I can’t speak for other Canadian jurisdictions.