Some very good advice here! Working is always probably the best way to make friends (or even enemies!
) but if you're retired or running a business remotely like I am you have to get resourceful.
And remember, making new friends seems to get harder the older you get. When I first came to the U.K. starting at 18 years old I made friends real easily. I hitch-hiked all over and made friends with people who gave me rides. They in turn gave me addresses and phone numbers of their friends in the places I was going.
But now I'm much older (I don't hitchhike any more!) and it takes a lot more effort. Older people are more settled in their ways and are not as open and adventurous as they once were. So I no longer get a name and address of someone with a place where I can "crash", say, in Leeds.
The way that my wife and I make contacts now is through recreation. We've always been into air sports starting with parachuting, then hang gliding, then paragliding. People in these activities tend to bond well and it's always been a great way to make friends wherever we go.
On a long holiday in Devon a few years ago we started taking gliding (sailplane) lessons and that also led into new contacts. Sadly, we weren't able to continue.
But you don't have to risk life and limb (and we've sure broken a few over the years) to meet people. Any recreational activity or hobby that you can share with others will work equally well.
So if you find yourself feeling lonely in your new home you should look into learning or doing something that you've always wanted to do. That could be scuba diving, rowing or even a reading club.