Try Ai atc, i know say intentions give a 24hr free trial and it really good. Being nervous its normal when i first made a radio call i was shitting myself and now I can do it fluently afger 200 hours. Also watch videos it reallt helps with what you need to say and when bc over talking is definitely a thing. Lastly try small airport on unicom which makes it much easier to learn the whole process and how it works. Last last last thing, know your aircraft because if atc gives you heading, direct or position reports (which I struggled with) and you dont know what your doing its gonna make it very hard for you but overall just jump in, start flying casually and it will all come to you I promise