It's a good idea to have your financing in place before you look at homes because homes are bought and sold quickly. You could lose your dream property waiting to secure the financing.
The rule of thumb is that you should be able to afford a mortgage three times your income. Lenders subtract any debt payment from your income, so if you have a big debt, you have less income. and less house. I suggest taking a good look at your credit report and make sure that everything looks good before you talk with a lender. If something is not right, contact the reporting agency and get it fixed. Some lenders can assist with this process.
Don't forget to set aside money for closing cost just in case it's not offered in the contract. It's typically 1-1/2 to 2 percent of the purchase price.