Transfer money from UK (Kampala)

I am moving from UK to Kampala in August for a couple of years. I hoped to set up a personal bank account in Kampala before I left UK but have discovered that I can't do that until I arrive there. However, my main concern is once I have a Ugandan account, how I will be able to transfer a relatively large amount of money (to buy a car) from my UK account. Any suggestions from those who have done this?