You should always keep your car regularly serviced and in a road/track worthy condition, but for the avoidance of doubt please note the following requirements and recommendations:
Must be in good condition and check pressures. Do remember to allow your tyres a chance to warm up. Slicks are permitted on General Track Days unless otherwise stated. A Motorsport UK approved roll cage must be fitted when using slicks.
In good condition and best to check them occasionally through the event.
Suspension and steering parts will define how well your car handles on the track; always ensure that these components are in good condition.
Your engine will be under greater use than normal. Check all belts and fluid levels are correct.
BODYWORK AND CHASSIS
All vehicles must be 'closed-wheel' for track day events. Open wheels/single seater chassis are not permitted. All cars must have working seat belts regardless of age. The bodywork and chassis should be checked and in good condition. Vehicles must not exceed 1.85M in height.
Make sure that you know where your towing attachment is are located. Towing eyes need to be fitted prior to sighting laps.
ITEMS IN YOUR CAR
A simple tool kit is handy to have with you but before you go on the circuit make sure that you remove everything from the car that is not firmly fixed down. Pens and soft drinks cans can become lethal projectiles. Also make sure you remove everything from the boot of the car. In some cases this also means the spare wheel (remember that MotorSport Vision cannot take responsibility for belongings).
Lights must be in working order. Brake lights or rain light must be on the car.
ON BOARD RECORDING EQUIPMENT
Yes you can as long as in-car cameras and other equipment is safely and securely attached to the car only using mounting systems specifically designed for that purpose. Professional 'designed specifically for the purpose' suction mounts/adhesive mounts need a secondary secure fixing such as a tether. The event team do reserve the right to insist on adjustments or refuse use of the equipment if they deem it unsuitable/unsafe.
You must ensure that you have enough fuel at the start of each session. You are likely to use three times as much fuel as normal road driving. If you run out on track your car will be removed to a safe position. This is an unnecessary disruption for other track users too.
Insurance is not compulsory and is your choice. It is unlikely that your normal car insurance policy will insure you. There are several specialist companies who provide track day insurance such as A-Plan.