Im not a SAHM yet but I only work 2 days a week & dont have any friends in the area or friends that have week days off.
I go to the market once a week with MIL & SIL, if you have a hobby join a class, (some community centres offer cheap/free classes) and if you ask you could probly take the kidlet/s. Book clubs?

That failing add everyone from BB on msn and sit on the net all day!

I dont know if this helps or not, good luck with everything