What track day you doing mate?

Major check is wheel bearings! Seen a lot of people with ruined wheel bearings halfway through a day due to extra high cornering speeds they don't normally do on the road,

Another check is screen wash, as flat out you may need it especially this time of year with a likely wet/damp track with spray,

All fluids

Brakes
Clutch
Oil
Gearbox
Power steering

Tyre tread to make sure they will last the day AND GET YOU HOME LEGALLY! Easy to get carried away then realise there bald at the end of the day lol

Tyre pressures, best to take a foot pump as you may want to alter pressures to suit and return to normal to drive home

Make sure you have both tow eyes and have them fitted before you get out on track

Lastly empty all the loose crap from the car before going out on track