"JP, A lot will depend on whether you drive or trailer to the circuits. Here are a few suggestions that could get you out of a spot; Cable ties, tank tape, a couple of wheels nuts, a tube of araldite, Radweld (best not), a couple of jubilee clips, set of spark plugs, spray cans of brake cleaner & WD40/GT85, small tube of copper grease, spare ignition master key, master cylinder cap seal, couple of split pins, clevis pins, throttle return spring, something to bodge a cycle wing back on, spare brake fluid, some fuses and relays, some random new/used nuts & bolts, fuel pump....some general tools, a torch and a magnet on a stick, always saves the day. The list of parts is endless obviously, it's just trying to think of the simple things that you could fix that otherwise would mean game over, whilst keeping it to the bare essentials. And there's always someone willing to help." I always trailer my car to track days so that I can take various bits including a spare set of wheels with wet weather tyres and if something happens to the car I can get home easily. Some bits in your list I hadn't thought of so that's helpful thank you.