The Associated Press reports:

The British government says it will introduce a bill next year legalizing gay marriage – but banning the Church of England from conducting same-sex ceremonies.
Equalities minister Maria Miller said Tuesday the bill will authorize same sex civil unions, as well as religious marriages if religions decide to “opt in.” But she says the legislation will make it unlawful for the Church of England and the Church of Wales – the established churches in those countries – to conduct gay weddings.

Obviously, protection for churches that object is of paramount importance. But “banning” a church from being involved might sound a touch odd to American ears. This appears to be a function of Britain retaining its established church, and thus the government retaining a certain degree of control over its practices. As the BBC reports:

Other religious organisations will be able to “opt in” to holding ceremonies, Culture Secretary Maria Miller said.
The Church of England and Roman Catholics, among other denominations, have voiced opposition to same-sex marriage and are expected to oppose the bill, even with its caveats.
But some religious groups, including Quakers, Unitarians and Liberal Judaism, are in favour.
In her statement, Mrs Miller promised a “quadruple lock” to protect religious freedom, involving:
‐ No religious organisation or individual minister being compelled to marry same-sex couples or to permit this to happen on their premises
‐ Making it unlawful for religious organisations or their ministers to marry same-sex couples unless their organisation’s governing body has expressly opted in to provisions for doing so
‐ Amending the 2010 Equality Act to ensure no discrimination claim can be brought against religious organisations or individual ministers for refusing to marry a same-sex couple
‐ The legislation explicitly stating that it will be illegal for the Church of England and the Church in Wales to marry same-sex couples and that Canon Law, which bans same-sex weddings, will continue to apply
Mrs Miller said the Church of England and Church in Wales had “explicitly stated” their opposition to offering same-sex ceremonies, so the government would “explicitly state that it will be illegal for the Churches of England and Wales to marry same-sex couples”.
She also said: “I am absolutely clear that no religious organisation will ever be forced to conduct marriages for same-sex couples, and I would not bring in a bill which would allow that.

The rest here.