If left hand works well you'll adapt! If it's a bit weak there are some helpers possible.
For fun I changed my keyboard layout to something exotic and felt really handicapped at first (totally self inflicted, and not comparable at all to what you go through mentally). It's OKish after a month, and now I type faster than I ever typed on qwerty.
Mouse:
I think with 30 your brain will adapt very well to your left hand. If it's too weak maybe the fingers can do more work so a trackball or something could work. The switch to the left hand is a brainfuck anyways so it doesn't matter if you also change the device, just settle on one quickly.
If hand/arm are alright, but fingers weak: click with something else (e.g. your foot). I can research or build hardware for that. (cheapest solution: remove all but one key from a keyboard and use a tool to map that key to click)
Keyboard:
The most common fix I think is having a modifier to "mirror" the keyboard. E.g. when you hold space and press a button on the left side of the keyboard it will register the key that is on the right side of the keyboard. There is scripts for this readily available, just let me know if mac or PC and I can find one for you (or you google).
Editing:
For editing you'll need shortcuts. You could either try to change them or find a mouse that has a few more programmable buttons. If neither works you can probably script something.
If everything fails I'll build you bunch of stomp-pedals for the feet that register as a keyboard (like guitarists have; just for shortcuts, not for typing).