You mentioned that you did take classes some time ago so that means you somehow know the basics. But you’re likely to encounter this very common answer when you’re asking these people—no, it’s not advised to go kayaking alone, and this is for safety reasons. When you’re kayaking, it’s best to have a companion who will be able to provide you with the assistance you need in the event of an emergency.
That said, some enthusiasts like you would very much prefer to kayak alone and enjoy the calmness of a lake or pond by themselves. If you want to have the ultimate kayak experience, it’s best to find a place that offers kayaking adventures that are guaranteed safe. You can book one of the self-guided Kayaking on the Thames adventures from Back of Beyond UK. They have solo kayaks that are stable for beginners and those who haven’t kayaked in a while. You’ll also be around experts who can help you, and even if you visit alone, you’ll surely find yourself in the company of other kayaking enthusiasts.