Well I am a Satanist and in the UK, but don't make a habit of revealing it to all and sundry - in fact outside of the few CoS members I have interacted with here in Blighty I have never told ANYONE of my affiliations!

I would also suggest as Satanism is a religion of the individual the 'strength of Satanism in the UK' is down to each individual in their own situation.

Clearly I find Satanism a positive and productive tool in my life or I wouldn't bother identifying with it!