Hi i am a business manager at a car dealer. My advice would be to check your credit score first, most dealers have several strings of finance companies to use so they will most likely get you on (maybe if they deal with Blackhorse they will put you with them again) somewhere. Depending on your credit score the Finance house will band you and you'll either go through prime or sub prime. If its the latter the rate is likely to rise as you will be considered a higher risk. You should be ok though as long as you have paid the current loan without any defaults, and your last default was a fair few years back. At the moment credit companies are cutting down on the amount of high risk canditates/ bad debt they take on so i your score is really low you will be consider sub prime.
The only other option (last resort) call black horse and see what they will offer you.