No it's not always regular. A few have organized London meet ups in the past (that I know of), @allasyummyfood being the one who's probably organized the most in London so far.
I'm a big fan of these meet ups though, this was my fourth one, so I'm going to try and get people together once a month at least (if no one else is organizing one already) :)
We've (us ladies in the post and some others) just planned one for Fri 2nd Feb evening, details still to come, but hopefully you can join us!