Lessons
Reading and research is a good place to start, but Bartitsu is a physical skill that one needs to practice.
Getting Started
You can follow my guide for training in practical Bartitsu here: The Complete Bartitsu Study Group Guide. Solo training is possible, but you will never experience the reactions and interactions with another fighter without practicing with at least one other partner. Working with others in a study group can allow you to learn from their background and different body type, and they can give you feedback on your performance.
Ongoing Training
Skill development and confidence requires regular practice. I recommend at least once weekly sessions. You can follow my session outlines from previous posts on this site.