ARC card

Hello
I would like to give a notice for marriage but my passport is with the home office if I request the return of my passport, my application would be cancelled.
I am still having an application pending, so am afraid to request my passport back or certified copy.
I visited some law centres but they just say "Register office should accept ARC", but in fact, they don't.
I am having an appeal hearing soon, so before I lose the case and become an illegal stayer (of course there is a possibility I'd win, though!)I would like to get married.
Someone in this forum was mentioning they managed to get married by ARC, I would like to know where it is possible, or is there any other way I can get married without valid passport.
Thank you very much for your help.