I've done half a dozen track days in the last few months and I've consumed one set of tyres (to canvas) and a couple of sets of pads, and I've performed one additional oil and filter change. I wouldn't have needed to replace the pads twice had one of my EBC Yellowstuff pads not delaminated, shedding the friction material from the back plate

I am now using Bluestuff (bought before the Yellowstuff fell apart) and I'm considering Pagids next. I keep my OEM wheels solely for the track, and use CSLs for the road. This way I can wreck a set of tyres and still use the car.
I used to suffer with significant understeer, but I have markedly reduced this by fitting a strut brace, 15mm spacers on the front, and most importantly binning the OEM Contis in favour of PS2s on the front. Any residual understeer can be dealt with through trail braking or getting on the power earlier. When I have time I'm planning to pull the camber pins (increasing negative camber) to reduce both understeer and also rapid wear of the outer edge of the tyre. I have to take off the strut brace and spacers for the road to avoid additional insurance costs, but fitting these and my track wheels takes only half an hour at the start of the day.
I've also run a Westfield on track for about ten years, in the last few years often side by side on the same tracks as the ///M. I've never significantly worn a set of tyres despite driving at ten tenths on the track. Similarly, it doesn't consume pads or much fuel. Mr Chapman's theories on lightness and speed extend to consumables too...
I always insure my ///M but never my Westfield on the premise that I've owned the Westfield for a decade so a total loss would be the equivalent cost of less than £1000 per year. Also, Westfield repairs are somewhat less pricey. As I have a trailer with a winch for the Westfield, I would be able to get it home again except in the event of a severe accident when likely I would have more pressing priorities anyway... Single day track insurance varies from just under to just over £100 per track day for an ///M.
In terms of fuel, I expect to use 60 to 80 litres on the track (single figure mpg), plus that getting to and from the event.
I would
strongly suggest turning off the DSC or this will apply the brakes when cornering hard overheating them unnecessarily which will lead to fade and may shorten the life of your pads. Just make sure you build up speed progressively whilst maintaining smooth driving then you shouldn't come a cropper! I've unintentionally spun my Zed a few times on track, and it usually occurs through carrying too much speed into a corner (typically after a late overtake when the normal line into a corner may not be possible). Our cars are very forgiving under power, losing grip progressively unless you're really heavy-footed.
Always take it easy until your car is up to temperature, and always do a slow final lap to let your brakes and engine cool before stopping (when airflow will be nil). I would keep an especially close eye on the temperature guage if you're in the desert.
Most of all enjoy yourself and recognise when you and your car need a break!