We dropped income significantly when we had children as we both wanted to work part time around each other and them....it's hard getting used to less money but so rewarding being at home with the children.
The main thing is look at your outgoings. We got rid of all expensive phone contracts, TV packages, insurances we didn't need, memberships for the gym we never used. We now only have outgoings that are MUSTs mortgage, council tax, utilities, internet, car insurance.
Fortuantely for us it wasn't hard as we aren't big into watching TV so now just pay £20 a month for the internet, and we have a free sat box that works off the old sky dish so that gets us extra channels and we can record but no subscription fee. Mobiles are £15 a month for both of us with talk talk, again we're not big into phones and the like.
Also with utilities, see if you can switch. We went from paying £70 a month for gas and electric to £35 for both!.
Our biggest expenses are cars. We have no finance but tax, insurances are pricey with two cars.