A+E could be useful, but I will warn you, you will be there for literally HOURS. I have been so many times I have lost count. You need to speak to the community mental health team and impress on them how urgent it is you get help.
Sometimes calling NHS direct can lead to them making an emergency appointment the next day, but you could spend a lot of time on hold due to swine flu at the moment
SS may get involved, there didn't seem to be any rhyme or reason as to when they got involved with me, but it never got further than half an hour sitting having a brew with a social worker who could see that I was making an effort to get better so all was fine. Sometimes they would ring the HV or surestart to get them to give me more support, but only with my agreement.
I have mainly ended up in A+E when I just needed to calm the hell down, and a good few hours sitting in a room where they have removed anything slightly hazardous and either whoever you came in with or some nurse is given the unenviable task of sitting watching you being mad.
In conclusion, unless you actually feel at risk, or have completely lost touch with reality, I would try the out of hours service if possible before A+E. A+E isn't the end of the world, but it is a bit of a pain in the bum.
There is help out there, it just needs to find you. Sometimes getting help can seem scary, but even actually being an inpatient is more boring than anything. No-one is going to take your kids away from you or lock you up unless it is absolutely the only thing possible. And you don't sound like it is.