flashman... adult interaction? what the hell do you think mumsnet is for?
Seriously, I agree with everyone who has said to see how you feel when the baby is born, your DW may feel that she only wants to go back to work part time, or not at all. YOu may decide that you can never bear to be parted from pinky for even a second and leap into sahd-ness.
Things to be thinking about in the meantime are: nurseries, nannies, child minders, and if you do decide to be a sahd, parent & toddler groups, tumbletots, baby singing groups, things like that all give you a reason to go out of the house, and as a dad you will not go short of conversation from all those bored mums.
And, fwiw, I was a sahm with dd1 for a little while and it drove me potty, I couldn't wait to get back to work. But when dd2 and ds came along I would have chewed off my right arm to not have to go back to work. LUckily I still have all my limbs - and no job