With regard to terms and conditions I would suggest using notice lock does fall into the category of taking all reasonable precautions. When you took out insurance for the contents insurers normally require a 5 lever notice or equivalent as minimum at the point of entry. Did you you state that...
The right answer is your first line. Had the repair not been carried out then I suspect the landlord may have got the repair done but wouldn't be able to claim as it is likely, as you say, to be below his excess. As the work is done, he probable thinks by denying it the amount won't be pursued!!!