Yes, your 'creditworthiness' is one the two big factors which dictate whether you'll be accepted for a mortgage (the other being your 'affordability') – and one of the main ways a lender judges your creditworthiness is by looking at what's on your credit report.
As a poor credit history can scupper your chances of getting a mortgage, before any application it's best to check your credit file (for free) and then read up on how to get your credit report into better shape.