There are many who can sing very well in private but whose voice betrays them if they have to sing before even half a dozen strangers. It could be a simple matter of self confidence which will automatically increase when you start training and practice several different kinds of songs. On the other hand, if it is some intrinsic weakness of your voice then you should train under a proper voice coach of London . There are many kinds of exercises which can strengthen your vocal chords and sweeten the tone too. After all you do want to be able to sing with power but without sacrificing tonal quality.
Among other things you need to learn to modify your posture to increase the intensity with which you send a little more air pressure to your vocal chords. Your vocal chords hold this air back for longer which produces a sound wave of higher intensity, which means a note at higher volume. Large amounts of air does not equal greater volume. You need to train and strengthen the tiny muscles that coordinate your vocal chords. When you do this, your chords will be able to hold down more air, for longer. That is how vocal power is produced.
The truly knowledgeable voice coach in UK understands and would teach you the importance of singing at speech level. This means that you sing at the level you normally speak in. This would be beneficial when you intend to take very high or very low notes. Breathe deeply and relax your muscles, especially the neck muscles. Lip thrills or tongue thrills help to connect your breath with your vocals and muscles. Also to protect your voice you should take care to avoid thick drinks like milk, which can coat your vocal muscles, and alcoholic drinks.
Drink plenty of water at room temperature or which is lukewarm. You may add a bit of lemon juice if you like, but avoid fizzy drinks, fried food and ice creams like poison. Most important of all, practice every day but make sure that your throat does not feel sore.