Read this thread carefully:
Unfair deposit deductions
The specimen LBA (letter before action) included in that thread sets out in detail your legal rights in a situation where the landlord is alleging that you caused damage or disrepair.
In addition to the matters set out in that thread -
1. Where you have actual evidence that the landlord looked at the condition of the property at the *wrong* time, i.e. looked at it as it was at the time of a previous letting to someone else, that is good evidence to put before the court if you sue or have to defend a claim. The fact that the landord has looked at the wrong inventory (or "Checkin report") is a potential winner!
Even if he later tried to claim that he had not looked at the wrong Inventory report, there remains a possibility that his feeble "explanation" might nevertheless be rejected by the court.
2. Another potential winner is that the landlord would not be allowed by the court to make any deduction for damage that already existed at the time you moved in. If you have documentary evidence of damage that existed as much as 6 months before you moved in, you can show that to the court as evidence that *you* did not cause that damage!
3. Also, you are right to rely on any provision in the contract that imposes a time limit on the landlord. Do not agree to give up that protection under any circumstances!
As the Tenancy Deposit Scheme provides you with the option of "alternative dispute resolution" you have the option to make a claim against the landlord for return of your deposit under the Scheme, i.e. without having to sue in the Small Claims court. See this thread:
Tenancy Deposit Scheme
In that event, the functions of the court are handled by the ADR (Alternative Dispute Resolution) service, and the evidence you have obtained should be shown to the ADR adjudicator instead of to the court.
Advice & opinions on this forum are offered informally, without any assumption of liability. Use your own judgment. Seek advice of a qualified and insured professional if you have any doubts.