Morwen, thanks for satisfying our curiosity. Part of the fun at Mudcat is that we get a lively impression from many different persons who share our interest in music, and your video adds to that. For this purpose, it cannot possibly be "too bad", though we get no chance to see your chin (ugly wart there?).

First lesson: don't make excuses; only perform anything in public if it passes your own critical assessment, and if you are willing to let your audience be your judge.

I encourage everyone to sing and play. Enjoy it and do not ask anyone for permission except your housemates. It is even more fun together with other people. If you do not feel up to your own ambitions, take a good teacher, as JohnCharles said. You'll be surprised how high notes you can sing easily! Your voice has a good "projection", the price to pay is that you may have to work on your articulation harder than others.

Now for the song: being from an operetta, it needs accompaniment and some sort of acting. If you have no pianist at hand, use the MIDI file, which doubles as a metronome. If after keen practice you can sing to it exactly in time and in tune, you have gained a lot - the song is not easy at all, and the high notes are the least difficulty. Articulation and acting come next.

Have fun and let no one frustrate you. However, drop your other career only after you have become a musical star.