Noddle, which is part of Callcredit, currently offers free access to your report for life, and you can get free 30-day trials of more comprehensive credit checking services from Experian and Equifax.
It might be worth obtaining a copy of your report from all three agencies because they could hold different information from different lenders.
Checking your own credit report doesn’t affect your credit score, and you can check it as often as you like. It’s only when you apply for new credit that a digital footprint will be left on your file and disclosed in future checks.
If there’s an error on your file, or you disagree with something, write to the agency involved to ask them to amend it. Alternatively, you can add a notice of correction.