AWYRCYMRY,
I know how you feel. I had loads of worries before my first solo, like what checks did I have to do after my instructor got out, and would I have to make any special radio calls etc. Fear not! I assure you, your instructor will be at least as concerned that nothing should go wrong as you are. You will be well briefed, and told exactly what to do. I'd be surprised if it was more than one circuit, but you'll be told. If you need more exams than you've already got, I'm sure you'll have been told that too. If you KNOW you're due to go solo on your birthday, then you must be ready for it, but as someone else said, if the weather is unsuitable or anything else goes wrong; well, that's aviation for you. Have a chat with your instructor about all of this; he/she won't mind, honestly! He probably doesn't realise you're so worried.
After that.....enjoy!
