I am with Payne, why mention such a personal thing as your mental health? To me, that is Not the 1st (or 10th thing for that matter) that I want to learn about a new friend. Intimate details are for way down the road with couple friends. There is more to you as a couple than mental issues, right?

Someone mentioned MeetUps, something we have in the states in most cities, but you have Oxford! There must be many lovely things going on that you could get involved in. Find hobbies in common where other couples are likely to be. I met some great people at a cooking class & a whole different group at a volunteer post.

I understand this as my spouse has issues making friends at all. I need them/want them, he makes it hard. But I press on...
Good things are on the way, just be open to them...