Having moved a lot recently, I would recomend that you get professional cleaners in at the end of a tenancy regardless of if your contract requires it.
Firstly, it saves you spending the time cleaning it, and secondly, it completely removes you from any liability for the condition of the property once you leave. If you get it professionally cleaned and the landlord isn't happy about the condition, their issue is with the cleaning company, not you. Yes it might cost you a bit, but it saves you time and means the landlord can't come after your deposit.
Firstly, it saves you spending the time cleaning it, and secondly, it completely removes you from any liability for the condition of the property once you leave. If you get it professionally cleaned and the landlord isn't happy about the condition, their issue is with the cleaning company, not you. Yes it might cost you a bit, but it saves you time and means the landlord can't come after your deposit.