I go for my usual advice on list making! So, if you have the two lists, one of things you enjoy doing or belonging to, and others that dont interest you. folding them over after each entry.as and when something occurs to you. Each do your own lists, and then on a wet and cold day, that is a good time to open up the lists and see what comes over as important to you. So if you have a favourite hobby, it may not be paramount importance now, but as you retire, being able to continue in your local area makes a difference.
Definitely I would study the public transport there is now, and try to see how it might become better or worse in the future. Whilst we need to be optimistic and look forward to things, in this case it is worthwhile just thinking of the pessimistic point of view. So think how you would manage if your eyesight became poor and you were unable to drive etc. Then you could also look at where any close family live and see if your planned area has good access to their areas. Whilst now you may think nothing of driving 100 miles to visit, just consider if they normally visit you, or how you would travel comfortably to see them.
This way if you have looked at two or three areas, you might then see that one area would not suit you at all practically.
The next idea may sound a bit odd but I can assure you it can pay dividends. So when you have found a possible town or area then go and have a B/b in that town in such as november or february for a few days. Everywhere can look lovely and full of life over christmas or in the summer. What is it like on a gloomy winters day? Are the shops all still open, are their clubs and things like swimming pools and leisure centres close to hand. Look round and see if the bowling club or the bridge club are active and busy. Things like clubs and the library become more important at that time of year to keep you active and interested. If you belong to WI or Rotary or whatever check if there is a group in that area and they may give you good information about living there and have knowedge of any major changes likely to happen shortly.
If you begin to look at these things now, you can take your time and compare both what is available and the costs of property etc. Much easier than that possibility of maybe something causing early retirement or illness meaning that your needs are different to your previous life. Also as you do this, even though it wont matter now, look at houses with thoughts of how you would live there when you are 90! What are the stairs like? Could you easily sleep downstairs if you needed to etc.
this does sound a bit doom and gloom but it can be interesting and exciting, and you may be surprised by finding that somewhere you had not thought of actually meets your needs much better than somewhere that looked better until you looked into it. Hope that even if this isnt of help to you, it will help you to look at what is important to you and look at new areas, with an eye to whether it can provide you with what you need. The best of luck to you.