You must do a daily walkaround check before you take your vehicle out on the road. This video shows some of the main checks to do. Check the guide on GOV.UK for the full list. On the outside check for any signs of damage and make sure things are secure like the grill bumper number plates mirrors wings wipers spoiler battery fuel cap and exhaust stack pipe too. Make sure the air, electrics and ABS are plugged in correctly and not twisted or damaged. Look at the wheels and tyres make sure there are no bald patches, the tread depth is adequate and the wheel nuts are secure. Also, check the spray suppression is clear from debris. Inspect the brake discs. They need to be in good condition and not cracked.
Underneath your vehicle check for signs of a leak. This could be oil, fuel or water. Look for damage on the outside curtain or panels and make sure the outline markers on the trailer are secure. Check the trailer coupling too these have safety locking devices so they don't come undone. Look at the airbag, this is the suspension of your vehicle, make sure it's in place and secure. Check the landing leg on the trailer is safe and check the under run bars and chassis underneath. Before getting in the cab, check the steps and handles are secure. When you're in the cab make sure there's nothing loose and your vision is clear including the view from your mirrors. Check there are no cracks in the windscreen and the wipers and washers work as they should. Make sure the drivers seat is in position and secure. Check the seatbelt for signs of cuts, fraying or other damage. Plug it in and check that it works. Look along the dashboard, you should test things like the hazard warning switch as well as your lights. You might need to get someone to help you check these from outside.
Check your gauges work and that they light up. Check the steering wheel for damage. Then check the stalk switches and horn. Make sure the gearstick is safe to use and the handbrake is in the ON position. Check the pedals to make sure your feet don't slip off and make sure the footwell is free from rubbish. Test the brakes and keep an eye on the air gauges. If they drop it could be a sign of an air leak. Also, make sure your tachograph is working and your vehicles height indicator is set correctly, where you can see it. If you find any defects, report them and don't take the vehicle out. An unsafe vehicle can cause death or serious injury. You can be fined for driving with defects, up to a total of £1500 depending on how many defects there are. You can be taken to court for serious offences.