Not sure road bikes are suitable for Mike.
Hard on the bum and privates, generally uncomfortable especially for a n00b.
S/h MTB is the way to go, far more comfortable to ride, and an easier option for a bit of exercise.
As an old person, I've sold a my road bikes, just kept a Giant hybrid and a Merida Matts MTB.
You really need a bike with front suspension and wider (comfortable) tires as you get older.