In my experience, I think overcoming nerves is nigh-on impossible: they are always going to be there. The problems really occur because of the self-doubt they induce, so if you can gain enough confidence to know that you
can perform what you've been practising they become less important. For this, I'd recommend getting as much performance experience as you can really helps on this one. Play to anyone who's willing to listen, and - of course - take advantage of opportunities like the Adult Learners' Concert if you can make it.
I played the organ in church every week for three years, and for two years played the piano in a retirement home for an hour each week. At first, I was truly nervous, even though I knew how much I'd practised; once I'd been doing it for a few months though, I became quite matter-of-fact about it despite the nerves and now quite enjoy performing - I play far better when I'm wearing something smart and have an audience, it's just a frame-of-mind thing. So perhaps consider doing some volunteer work - learning various older songs will give you lots of music-reading experience, and playing them in public will help you with performing.
I wouldn't mind appearing in the concert it may boost the confidence thing,I have appeared in a music festival before where i actually came second when i was 14