How to tell parents you want to pay for your own wedding

Long story short my dad is very volatile & can go off on one at any moment. We've always had a tense relationship and see each other maybe 2-3 times per year. I have managed to keep my fiancé away from seeing the drama for 6 years (he sees my parents at christmas) but he is aware of how my dad is but always made light of it (maybe thinking i was over exaggerating the stories/my feelings)


We had already decided we wanted to pay for the wedding ourselves as we have the money and he doesn't want his parents to contribute as he's been married previously. Accepting money off my dad is like making a deal with the devil as it always gets used against you.
Anyway my parents came over last night & we went for a lovely meal which was going so well, even talked wedding stuff & dad offered to help out......then he nearly got arrested for causing a massive row with a young waiter for being charged £1 for an extra pot of gravy. Yes that's right £1 I was mortified, embarrassed, ashamed & am utterly convinced that my partner does not want to marry into my joke of a family. He was horrified at how my dad acted & now understands what i have protected him from this whole time.
We want my dad to contribute nothing to the day so he can't complain / kick off. We have already chosen our venue & paid deposit & i'm debating telling him that we have paid for the lot already so he can't.
Our wedding is still 2 years away & i'm upset that he has taken the shine off my engagement and i'll be stressing for 2 years now about any interaction with him especially in front of my partner who i think is still dumfounded at what happened last night! How can i tell my dad in a polite way that we don't need financial help without offending him or causing a row?
Thanks for reading