If you're a visitor to the UK, you can use a vehicle displaying foreign plates as long as:
If you become a resident in the UK, you'll need to tax and register the vehicle straightaway. The same applies if you want to stay for longer than 6 months, but certain students and workers are exempt.
If you're stopped by police because your vehicle has foreign plates, you must be able to show that you can use the vehicle in the UK. You'll need to show proof of how long the vehicle has been in the UK (such as a ferry ticket).
Certain vehicles will need to display a temporary Q plate, e.g. those showing non-UK identifiable letters and numbers.
If your vehicle is registered outside the UK, you might be eligible for relief from custom charges if you intend to use the vehicle in the UK temporarily. You would do this by completing the online form.