Your responsibilities depend on the lease.
For a short-term rental such as serviced offices, you might only be responsible for internal decoration, with other maintenance and repairs being the landlord’s responsibility.
With a typical commercial property lease, your obligations can be much more extensive. With a ‘full repairing and insuring’ lease, you are generally responsible for internal, external and structural repairs and maintenance. Or you may only be responsible for internal repairs and maintenance, while the landlord maintains the structure.