right-hand-side car

It is much easier to buy one in the UK because then you won't have all the hassle of reregistering it when you get there.

Agree with Becasse. Just get one there, it will be cheaper and much less hassle.

Selling your Belgian registered car here in Belgium and buying a British registered RHD car in the UK is the only easy way to do it. I suspect that you would have difficulty here in raising the finance to buy a RHD car once they realise that you want it because you are moving to the UK.

Have you thought of buying secondhand in the UK to keep costs down, which would have the added advantage that the car would be available to you as soon as you could arrange insurance.