If you want to take up jumping, I'd get lessons. There's a lot about it that isn't intuitive, and it can be hard on you and on the horse to teach yourself the wrong way. Plus hard to undo bad habits later.
Also, if you're used to riding on a loose rein, then lessons on how to communicate via a steady rein contact would be a good idea. A lot of that isn't as intuitive as it looks, for example using the reins to control the shoulders, outside rein connection, etc.
But it all depends on what you want to do!!