Welcome to the joy of two wheeled transportation, Dan.
Safety is your most important concern! Getting used to your scooter is part of this so do as Agent bob suggests and practice in some area where there is no traffic such as a vacant parking lot on a Sunday for instance. Practice a lot!
When you do go out on the roads, car drivers are your most dangerous opponents. Many, and I do mean MANY, simply do not look for or see scooters or motorcycles! Never take their actions for granted. For instance, you may think an oncoming driver will wait for you to pass before turning. There is a good chance they will NOT, and turn right into you! Anticipate this at every instance and be ready to brake hard, sound horn, evade, whatever.
There is a reason you see many bikers wear brightly colored clothing and accessories. Get yourself some of the most brightly colored clothing and helmet you can find and wear it while riding.
I'm not sure how much joy can be experienced on dense urban roads such as in and around a large city like London. I hope you get chances to get away from the city and out on to rural roads where, in my opinion, the true joy of riding is to be found.
Congratulations, Dan, and again, welcome!