I need advice and help with buying a business

It is an internet cafe with 7 computers and a 2 bed flat above. The flat is not in good condition. the asking price for the 18 years lease is £26000 which does not include stock. I need some help in what I need to consider in making an offer.The current owner is disolving the business so I will have to continue the business with a new registration. It is the first time in this kind of process so I need proper guidance