You'll meet skaters who have never had a single lesson. They get from A to B with a smile on their faces, so who needs lessons?Well, as with any skill, there are lessons to be learned and a good teacher/instructor will fast track these for you and give you instant expert feedback based on years of experience and (no doubt) other instructor's lessons. Lessons can cut out seemingly eternal trial and error learning and, importantly, lessons will stop you learning the basics badly.
There is a right way of doing things, and the right way looks right and feels right, but there is no guarantee that you will discover it by trial and error. It always makes me wince to see an experienced skater limping along with bad technique when, after guidance from a good instructor, they could have been gliding. My advice is to get at least a few lesson, learn the basics and then see how you feel about doing more. Some people become dependent on an instructor, when really you should see them as a resource that you can dip into.
You can also pick up tips and tricks from other skaters. If you go to the bigger London parks you will meet loads other skaters (it's a very sociable pastime) and skaters will be happy to show you how to do things. Just say ‘hi' and take it from there.