some things to add

Workshop tools:
the general screwdriver, alien keys, sockets + wrenches etc...

Emergancy Repair tools:
should also consider a couple hammers as well for DIY panel beating as a worse case scenario if anything happens. Also include things like cable ties string, duct/speed tape, spare wire and possiably silicon/hot glue gun.

Just as a side note, if your going up to the track in a slighly older car, you may want to consider some kind of roadside assist. eg RACV,NRMA, RACQ as my mate had a car towed back ~300km's from winton raceway. but thats only provided it 'breaks down' and wasn't involved in an accident.