Can i arrange a surprise wedding in the UK?

My other half has been banging on about us getting married for years. Im not the kind of girl that is into big showy weddings...i have always said no whenever he has asked me, but i know he would love to get married. i adore him and decided id quite like to get married too....but id LOVE to surprise him. do i need to have his signature on anything to book a registry office? i really want to surprise him!