I am looking to sub-let my apartment for a few weeks over Jan. Do I require some sort of insurance to cover myself, should the sub-letter have an accident?

You should ask your sub-letter to provide you a copy of his valid liability insurance policy - just in case something happens to the apartment due to his fault. In general, I recommend to have an insurance policy in place for yourself, as well. Further, most probably, you have a clause in your rental agreement saying that any sub-letters should be approved by your landlord in advance...

Hi Guarana, Thanks for the great reply! Much appreciated.