father I am in a similar position. I have a 8, 6, 4 and 2 yo and am a sahm. I've contemplated doing a pgce, but there is a very interesting thread ATM about doing a pgce with a family. I must admit I just don't think I would manage.
In the past 12 months, my two oldest have been diagnosed with additional needs, both very different in nature. It's involved dr appts on an almost weekly basis all year. I don't know how I would have managed that as a working parent. As it is, dh has used lots of annual leave for childcare as I'm never sure how long appts will go for, one dc was likely to be admitted to hosp and we have no family in the uk.
However, I have found a part-time course I am interested in doing, that will probably only ever lead to a part-time Job. It's a far cry from what I used to do, which is great. I guess dh will need to be more flexible when I start the course (presuming I get in).
Quite apart from all the appts, I need to do physio with one of my dcs 5x a week, I've been nit combing hair pretty regularly recently, I've brought all the Christmas presents. Dh will need to pick up more slack (very poor eyesight, likely to eventually be legally blind in a couple of decades). As a pp said, I'm hoping this will be easier as they move into their teenage years (though one dcs condition will probably get worse). Anyway, I was pretty fortunate to find the new course, and I hope to start in spet 2015.