Try to get ahold of either Hybrid or Innovative. I know between the two there are some spare scooby wheels/tires on rims.
They may be crap but better than chunking up snows.
You can get by on street pads, but like I said before an extra cheap set of pads is good insurance, and you could always return them if you did not use them.
Even if you start to feel fad, just come in early. You do not have to be out there your entire session.
Some track time > no track time at all.