If you want to race a TTR 110, you can race a TTR110. Throw some street tires on it and come out. You'll also want to at the very minimum safety wire the oil drain bolt/fill cap and remove the kickstand.
Depending on what is done to the bike will determine which class you can run it in.
StockMoto and F3 are the classes you'd likely run.
Here are the stockmoto rules in regards to TTR110
If the bike isn't setup to the above rules, you can race it in F3.
Textile is fine for your first race, but just a reminder that if you crash, it could end your weekend if the suit doesn't hold up. Watched @what crash in a 2 piece speed & strength leather suit and the zipper completely destroyed and ended his weekend. Just figured I'd throw that out there. We are really lenient on a lot of things and everyone will go out of there way to ensure you can race and be safe. Just keep general safety items in mind and you won't have a problem.
Also if not having the bike is the issue, a lot of guys will let you run their CRF's on practice day to test it out and if you really want to go all out I'm sure someone will have a rental bike you could rent for like $60 for the weekend.