Read the check-in inventory before you clean anything, because it is the document you are measured against and the first thing an adjudicator reads. On the day you leave, photograph every room in daylight, match the angles in the check-in photos, and photograph the meters.
If a cleaning deduction is proposed, ask for it itemised with the evidence behind each line before you agree to anything, and say in writing if you disagree. If you still cannot agree, the scheme decides it for free and the disputed money stays with the scheme until it does, so contesting a wrong deduction costs you nothing but time.
Whether you clean it yourself or book someone is your call, and the law is neutral on it. Our printable checklist covers every line an inventory clerk checks, free. If you would rather buy the time and the paperwork, that is what we sell: a fixed price, a timestamped photo record and an itemised receipt.