I want to take the test and don't want to take the test; don't mind registering with the bbc. I've always thought that I can tell off key notes - which is why I have always hated my own singing efforts. The last thing I'd do is annoy myself in the shower by singing..
I sang in the choir as a kid and I don't know why they didn't toss me out of the loft down to the pews, especially the time I sang a funeral mass alone. I hope the organist was extra loud..
On the other hand, I wasn't all that awful with the piano, taking lessons four years or more. Not saying I was great either, but I got a lot of pleasure out of it when I did practice.
In later life I had a friend who was a superb pianist, having studied with a famous teacher in Paris to be a concert pianist. He had trouble with performing before crowds, if I remember. But.. he had perfect pitch. I never sang around him... I didn't want to see a grown man barf at the sound of my voice. He ran a lab across the hall. Thinking, I never sang in the lab either. What a thought.. that would have probably caused the liquids in the flasks to swirl.
I've known people like that with drawing - uncanny hand eye coordination and sense of scale.