I'll answer both questions:
what are the ups and downs that I should expect on doing my PPL?
cjm2010 pretty much nailed it with his answer. You'll have a lesson where nothing is going your way, you are miles behind the plane, you can't do anything right in your instructors eyes, you forget everything you ever knew about flying and your performance proves to you that you'll never be able to fly, ever. Then you'll have a lesson where you do so well they might as well hand you your license right now because flying is as easy as breathing.
Its all about picking yourself up after a bad lesson and looking forward to the good lessons to come.
What are your experiences of your first solo flights and circuits?
I learned to fly in a busy circuit, so I was used to sharing it with other aircraft. Fortunately I was the only one flying at the time when I went solo. While I remember every second of my first solo, two impressions stand out. One, the aircraft performs differently with only you in it. And two, I found myself coaching my own approach, saying things my instructor would have said. Apparently this is quite normal.
