When you go to a mortgage broker, they'll work out how much you can afford to borrow based on your household earnings. But, it's important to take your overall budget into consideration too. Think about how much you spend on your bills, groceries, transport and children every month. Then think about one off costs, like birthdays, holidays and Christmas, and remember to add a monthly amount for those expenses into your calculations. If you haven't owned a property before, don't forget that you'll have to pay rates on your new home and you'll need life assurance, buildings insurance and contents insurance.
You can use the Mortgage Affordability Calculator from the Money Advice Service to find out how much you can afford to borrow, how much your monthly repayments are likely to be and how these repayments will change if interest rates rise.