Totally agree with the deliberate/slowed down advice, if you can think of the people there as your friends without being overly friendly in what you say that will help to relax you a little.
So don't think too much about who they are, just that they are ordinary folk same as you and I, two arms, two legs etc.
Think about your syntax, don't make yourself look silly by making grammatical errors or make a simple sentence over complex and/or ambiguous or repetitive. Concise and to the point can sometimes be the best way rather than over elaborating, however too concise and it sounds like a mandate, it can be hard to strike the balance and it often comes with practise but some people can just do it easily.
Write/type your speech in big bold letters with wide paragraphs (this is what politicians and heads of state do), underline a sub heading if you like, so if you do forget where you are it should be easy for you to find where you're up to. If you have 5+ sheets of A4, it doesn't matter.
You could practise in front of people you know, then if you want maybe even down your local.
No-one is expecting you to be the next great orator or Martin Luther King, however your belief in what you say if said with passion & empathy for the cause will have an emotive effect on the people regarding the message you are giving or at least make them think much more as opposed to just delivering a monotone speech.
I've always been a natural chatterbox, I loved debating at school and in my career doing staff training, presenting contracts and other guff to all & sundry but there's always an element of nerves so don't worry if you get the jitters a little.
Suck on a throat lozenge and if poss maybe even have a glass of water to hand (It's surprising how dry your throat can get at the wrong time when you're a little nervous.
Lastly, smile and try to look around at the people when you speak, it has just that little bit more personal meaning if you look into people's eyes when you say stuff but don't hold their gaze too long.
Sorry that's a shed load to take in.
Hope it goes well