This depends on the terms of the lease. A 'Fully Repairing and Insuring' lease makes you liable for all maintenance and insurance costs. You will usually also be liable for alterations and repairs needed to comply with legal requirements: for example, if asbestos needs to be removed or made safe or if the premises need to be made accessible for disabled people. At the end of the lease, you may well be responsible for reinstating the premises to its 'original condition' or even to renew or rebuild (or be required to negotiate a suitable payment to cover any 'dilapidations').
In shared premises, tenants are usually directly responsible only for internal repairs. Even so, you may also be liable to contribute to maintenance costs. In circumstances like these, it is important to investigate the state of the premises and what maintenance plans the landlord has, as you may end up being charged for any maintenance works.
