It depends on the terms of the lease. Most leases will impose some repair and maintenance responsibilities on the tenant. Your responsibilities might be as limited as updating internal decoration from time to time, or include full responsibility for internal, external and structural repairs and maintenance.
Unless you have completely fulfilled your repair and maintenance obligations, the landlord will usually be entitled to serve you a schedule of dilapidations detailing the work that is needed and the estimated costs. This can include requiring you to reinstate the premises to its original condition if you have made alterations — even if the landlord consented to the alterations.
If you fail to carry out the required work before the end of the lease, the landlord is likely to claim damages from you to cover the cost of putting things right. In some cases, however, these damages could be lower than the cost of doing the work — for example, if the landlord is planning to redevelop the premises anyway.
In most cases, the landlord and tenant will agree a payment to cover any dilapidations. If you are approaching the end of your lease term, or have been sent a schedule of dilapidations, you should take advice. Your lawyer can work with a local chartered surveyor to negotiate a fair outcome for you.