A campaign to overturn the bans on gay marriage and heterosexual civil partnerships is to begin next month when eight couples will file applications at British register offices for ceremonies they are presently not allowed to hold.

Four same-sex couples will apply for civil marriage and four heterosexual couples for civil partnerships. Each week, up to 14 December, one of the eight couples will make an application. The campaign's co-ordinator, Peter Tatchell, said there was growing political party support for an end to the bans as well as public support for same-sex couples. "Our aim is to overturn both the ban on same-sex marriage and the ban on opposite-sex civil partnerships.

"If they are refused, as we expect they will be, we plan to mount a legal challenge. We believe these bans violate the Human Rights Act and are open to challenge in the high court," said Tatchell, of the lesbian and gay rights campaign group, OutRage! "Civil marriages and civil partnerships should be open to everyone without discrimination."

The Rev Sharon Ferguson, 52, and her partner, Franka Strietzel, 49, will be the first couple to lodge an application, at Greenwich register office in London. "A civil partnership doesn't feel comfortable for me; it doesn't fit. We want a marriage – that is the institution we believe was divined by God and for me that is important, and I don't see why we should be denied it because of our gender," said the Metropolitan church minister.

"We have a double system and we shouldn't have. That isn't equality. Love is love at the end of the day and that should be honoured."

A Populus opinion poll in June 2009 found that 61% of the public believed that, "gay couples should have an equal right to get married, not just to have civil partnerships".