In reply to Will Cat:
Well, it's one holiday when you don't mind spending plenty of time indoors.
We had two weeks in the Scottish Islands, and only one day when it didn't rain!
No idea on the budget, or the scale of the wedding, but if it is likely to be stressful for your other half then it might be an idea to go somewhere with relaxation and pampering available.
Langdale estate might be worth considering, either rent a lodge or spend a few nights in the hotel. Has the advantage of one of the best pubs in the Lakes (Britannia at Elterwater) on the doorstep.
If you want to get away from it a bit more, then maybe eskdale or wasdale