Well it gets tricky here. The Queen is Supreme Governor of the Church of England, and the head of state of the UK (the Queen/King) has to take an oath to defend & uphold it (i.e. no catholics allowed to be monarch), though they are changing that.

There is also a Church of Ireland (which was disestablished as the offical religion of Ireland (which was in the UK) in 1870ish), and Church in Wales. Scotland has sorta it's own church (think it's a slight different variant) which it has a right to exist due to the Act of Union of 170x.

So it's all a bit complicated and depending on how you define "UK" and "UKwide"

I think the members of the Church of Scotland would object rather strongly to being described as a "slight different variant":

http://en.wikipedia.org/wiki/Church_of_Scotland

NB Although I've always been an atheist, I grew up in a small community in the North of Scotland dominated by the Kirk and it's more zealous offshoots. If you've seen Lars von Triers "Breaking the Waves" then you'll get the idea.... :-)