Hello MightyDucks,
1. Don't worry - I am one of the few people who have been sick while the CFI was flying (first lesson- effects of controls). A wee bit of un-cordinated flight (on purpose) combined with over-excitement due to the anticipation of the flight. I got quite worried about what might happen on subsequent flights, but didn't need to be
2. Get some wrist bands for air/seasickness - I eventually got rid of mine after the tenth or so flight and was fine
3. Take travel sickness tablets (again, found I didn't actually need them)
4. Make sure you have a bag ready (just in case)
5. Eat something 30-60 minutes beforehand. I suggest a banana (don't ask why!)
6. Ensure you have a supply of cool fresh air
7. Wear loose-fitting clothing that will keep you on the cool side of warm
8. See if you can sit in the aircraft for a while on the ground (obviously with the instructor present). Get used to the sight/smell of the aircraft and also the instruments and maybe also the seat harness. A non-flying day would be good for this (wet or a hazy day with no horizon)
9. And relaxxxx...
Been there, done that, now got the licence. I'm not the first and you're not the last!
Have fun!