45 colt is not too much to handle at all. When I was learning on my large S&W (great company by the way) I was shooting 38 special through it (you can do that in a .357 revolver) and at the time I was concentrating so hard I couldn't tell the difference when a similar model in 45 Colt was handed to me. They can be loaded VERY hot if so desired or pretty mild from what I understand. A used steel S&W revolver is great as a lot more hand fitting and attention went into it and was one of my first guns. A friend of mine uses a large 45 Colt revolver for home defense. Big bullet.
If you learn to shoot with a revolver your trigger control discipline will be above average when you get into semi autos. Assuming you make progress - and you will.