Hello Peter, lovely to have you on board all the way from the other side of the pond as it were.
As a Coach I have several shall we say "more mature" shooters coming to see me regularly and are enjoying it immensely.
The main problems they have is focussing on certain types of clay targets and restriction of movement or being quite stiff.
Clay shooting though can in fact loosen you up a little as well. I get my "more mature" pupils to do a few minor stretching exercises before shooting at all and then a few more before certain targets so they can swing better etc. Just about all of them say they are a little looser than when they first started shooting.
Also a real problem can be recoil if using a heavy load. But these days there are many recoil reduction devices you can have put on your gun as well as lighter loaded cartridges with far less recoil but still kill a target very well at 60yds.
But there are plenty of targets out there that the "more mature" shooter can hit and hit very well indeed.
You don't have to hit every target to enjoy yourself, in fact that gets boring after a while believe me...
Don't buy a gun that's too heavy for you. If your still very fit and healthy then a gun around 8 pounds or a little less will do a good comfortable job. Anything lighter than about 7 pounds will have a few problems with recoil unless your a big guy, but even then it depends on your physical condition.
Practice your gun mount at home several times a week for 10-15 minutes in order to build muscle memory and the muscles themselves.
One of the best things about the sport is the new friends you make while Clay Shooting, many staying good friends for ever.
So get out there with a good attitude and shoot some clays, enjoy yourself and make new friends.
Good luck.