I don't know of any really other than here and the green site.
I used to use several parenting forums that had working from home sections but they are pretty dead these days, they used to be so busy and full of people helping each other out but people have just disappeared over the years. I used mumszone, parents lounge and mums club. I still post on baby centre from time to time but the work from home section is pretty naff.
I signed up to WAHM http://www.wahm.com/ for a bit and posted there but it is 99% American people posting there are a lot of what they discuss is either completely irrelevant or not available for UK workers, so I got a bit bored with it!