My suggestion is to maybe look for something you enjoy, and already do, or have missed doing since you were alone. So for example, you might be a card player and there will be bridge weekends or whist weekends . Or you may like to visit gardens, where you might find a trip that goes to a RHS garden that you havent visited before, or which may have been a bit too far to drive to . Another possibility at this time of year is to look to see things like courses being held, such as a musical one, where there is chance to learn a particular piece , either singing or with an instrument, Folkworks used to do weekend courses which were brilliant, as they had different classes for beginners, or intermediate or people who were good players but didnt have the opportunity to play in an orchestra or band. What they did was to have very good teachers who were musicians themselves, and each group would learn appropriate music for their level and then on the last day everyone would play together, obviously simple parts for the beginners and more difficult for the more advanced but you all shared playing music together. A weekend like that can also lead to meeting other musicians in your area, with a chance to continue meeting at a later date.
Doing anything like this can give you confidence in that you know something of the subject, and already speak the language , so to speak, so you already can relax a bit as you are not jumping into a total new situation. This will mean that you will find mutual places or interests to share with people. This can be a stand alone time , or it can lead on to further times where you will already know some of the people who go to the next one.
Another idea could be if you are interested in any genealagy or want to find out more about your ancestors, you could choose to go to somewhere that has meaning for you, so that you already have a reason to be there, which can help you to venture out and about. I would tend to look for something that was your interest rather than both you and your husband, as you may find that there is something you never really followed before, and having no connection to your husband can be a help.
When you look at your options, however hard it is , if you dont take the plunge, are you just going to stay in your home, never going anywhere new, and getting more worried about trying it? So if you try to go to anything, even if you dont like what you do, that doesnt matter really, as the main point is to try something. Either way you will be the winner. You may find something that you are excited about and want to keep on with it, or you think that was rubbish and I wont do that again, but even that means you will now turn in other directions and look for something else. Just have a think. Was there anywhere that you always wanted to visit, and never managed to get there? Well perhaps you have a friend who also wants to see that too, and you can try it out, In the worse scenario, you get there and dont think much to it, but then it could be lovely and you can then go on to further trips.
Good luck
