Current or historic financial credit problems are more likely to affect first time buyers than those looking to remortgage.
A bad credit remortgage will normally involve a higher rate of interest than the current mortgage, especially if the adverse credit marks have occured since the original mortgage was advanced. If you are in mortgage arrears the current lender may no be willing to remortgage you and therefore you may have to find a new lender. Indeed, since he 2008 credit crunch hit many previously available mortgages have been removed from the market.
Finding a new mortgage with a new lender can be a time consuming process. Each lender will ave different criteria, offer different rates, and charge different fees and penalties. A mortgage broker may be able to help you choose the right deal, whilst saving you a lot of time. Do beware of brokers charging large fees. Some will attempt to charge several thousands of pounds, making the remortgage uneconomical.