If you are a resident in the UK (which for this purpose includes if you just moved there with the intent of working and living in the UK), you cannot drive a non-UK car in the UK. Since there are no residency cards in the UK, whenever you are stopped by a police officer and he thinks you are actually a resident (for example if you have a UK driving licence, or have UK debit cards in your wallet), then he might confiscate your car which might be destroyed, unless you can prove you are not a UK resident, or you are working in more than one EU countries, and spend more than 6 months (185 days) per year outside of the UK.
If you are not a resident, then you can drive the car for at most 6 months (per year), but your car does need to have valid MOT and Insurance from the originating country, which you have to prove to the officer in case it's needed. You also have to prove to him that you are not driving the car for more than 6 months (for example if you show him the ferry / tunnel ticket). Every day your car is in the country counts, so if you leave the country, but the car is still there, it's still counts towards the 6 months (as your ferry/tunnel ticket is still showing the date). Exiting and re-entering the country won't reset the 6 months (although you will have a fresher ferry/tunnel ticket, so it becomes easier to prove you just arrived to the country)
There are only three possible options for a UK resident to drive a non-UK car completely legally:
- If the car is not yours, the registered owner is not a UK resident, and he is sitting with you in the car (in this case he is considered to be the driver)
- If the car belongs to (or to be more precise is registered in the name of) an EU based company, and you are working for that company.
- If the car is on a lease in an other country (for example it's a car hired from France)
The second point is regulated by common EU rules on using non-local, but EU-registered cars abroad. Note that these EU rules also allow students, who are enrolled in UK and are only studying in UK for a set period to use their non-UK car. This is because they can be considered as non-residents.
Note: the above does mean, that if you are a UK resident, and want to import your non-UK car, you cannot drive it even to get it's MOT and registration, you have to tow it around, or ask someone who can legally drive it (e.g. a non-UK resident). From the government's site:
DVLA advises you to transport your vehicle from the port, rather than driving it.
Source:
Importing vehicles into the UK (gov.uk)
Excerpts
Driving with a foreign registration number
UK residents aren’t allowed to use non-UK registered vehicles on UK roads. The only exceptions are if you:
- work in another European Union (EU) member state and use an EU-registered company car temporarily in the UK
- lease an EU-registered car and use this temporarily in the UK
You can usually use a vehicle displaying non-UK number plates, and not have to tax or register it in the UK, if:
- you’re visiting the UK and don’t plan to live here
- you only use the vehicle up to 6 months in a 12-month period (1 single visit, or several shorter visits adding up to a 6-month period)
- the vehicle is registered and taxed in its home country
If you’re stopped by the police
If your car has non-UK number plates and you’re stopped by police, you must show you can use the vehicle in the UK without taxing and registering it here.
You may have to show proof of the length of time you’ve been in the UK (eg a ferry ticket) or evidence that you and the vehicle are eligible for customs relief.