Mortgage underwriting is vastly different from loan aplications. On a loan, the lender is really hoping that you pay back and the only recourse if you don't is registering arrears and ccjs on your credit file.
On a mortgage, as the loan is secured on land, the lender is in a much better position, as if the worst comes to the worst (from their point of view) they can always repossess your house and can guarantee that they get their money back.
That said, if you are showing on your credit searches as a bad payer, it will not be as easy. you are best off going to a mortgage broker who will be able to source you a lender who will look at you. You will pay higher rates than if you were "good payers".
The higher the deposit you have available, the better position you will also be in.
Hope this helps