Wow! I'm so sorry to hear this, I'd imagine this is somewhat taking the shine off your wedding planning.
How long have you got left to go?
I'm guessing your fiance is of a mixed heritage (i.e. mixed ethnicity or born British from an Asian family or something like that?)? You need to think about how your dad is going to be on the day as well - it sounds like he isn't the kind of person to keep his -let's face it- racist views to himself, and is that going to make your fiance and his family uncomfortable on the day?
If you have a bit of time, I would try and sit down with your dad (maybe your mum will back you up or mediate?) and ask him if he has any evidence to back up his comments, and if he hasn't, then call him out on it, and explain that his behaviour is unacceptable.
I would try reasoning with him first, but if you are genuinely concerned that his presence might cause upset on the day, then you may need to think about not having him there, but do try and resolve it first, as I think you will regret not having made an effort to have him there. Maybe you could get him to agree to spend some quality time with your fiance and/or meet your fiance's family beforehand?
This is a hard one, so I wish you all the luck! X