Are you able to travel to Gibraltar when the borders reopen/it's safe to? If you have until September, perhaps it's something to consider. My husband and I married there this past winter because it's easy to do, a quick flight from London, and they don't have residency requirements (you only have to show proof of hotel stay I think 2 nights prior or after your ceremony).
In doing that, you're not going through the trouble of potentially breaking UK visa rules and you get a nice marriage certificate in English, so you should ideally be exempt from the travel ban in the future, if it persists (I had the same question as per my other thread).
The other option is Denmark when they finally reopen or even St. Lucia - which I believe is reopening sooner rather than later.
I know it's probably not the wedding you had in mind, but I promise when you arrive there with your partner, you suddenly won't care about the rest.