For a married family with one income, Joint Assessment is the only practical option (Revenue leaflet IT2 "Taxation of Married Persons").
"The standard rate band for married couples for 2011 is €41,800 subject to an increase of up to €23,800 where both spouses are working."
Which means, i think, that currently your husband is paying 20% tax on the first €41,800. If you went back to part-time-work, you could earn up to €23,800 @ 20%.
Call up the Revenue helpline, I've found them very helpful.