If you are taking out a fixed rate mortgage the term of the loan is normally thirty or fifteen years. Bottom line economics, you will pay more with a thirty year term mortgage, generally double in interest payments. If you can't afford the fifteen year term payments, go with the thirty and get more month to month financial stability.
Here's an even better plan if you can manage it. Take out a thirty year mortgage but pay the difference between the two as principal. This way you can pay off your loan earlier but still being able to hold back if it's a rough month moneywise.