Hello Peter,
Welcome to the Restoration and dating board.
I'm not an expert by any means , and I don't own a tablet yet, but what I suggest is that you get to a level of colouring that you are happy with first. Then decide whether you are enjoying doing it , which I think is the main point. If you are already at this stage , then yes go after a tablet , otherwise it will be something to gather dust in the corner. It won't do anything for you except make it easier to do. (theory)
There are quite a few graphic tablet users on here , so hopefully , they will give you more detailed advice.
Jim