You guys are right about tradition, but I feel like, since none of my family are coming over due to financial situations, even though that's 'not on us' (we wanted to pay for my parents to come but it costs more than if we went over there, which we are doing for my 21st birthday), that having the cake be my choice of sponge, is a fair trade.....
And I think since I've got no american traditions, besides the mexican food for our reception dinner, that the family should be open to having something different, even though it's tradition.....
I don't know what british traditions besides the cake there is, so probably have to talk to him about that, so that he doesn't feel like I'm taking the one british tradition there is, away from him :p