Tenants Covenants
The (DDA) legislates against discrimination by a service provider but it is up to the service provider to decide how best to avoid being discriminatory and this may not involve the alteration or removal of physical features. On that basis a landlord cannot force a tenant to do particular works in order to comply with the (DDA) (even though the lease requires the tenant to comply with statutes) as the tenant may have an alternative way of providing the service without discriminating against disabled people.

Applying the same approach to dilapidations, the landlord would also fail. The fact that premises do not have ramps (for instance) does not mean that the tenant has breached the repairing covenant and that the landlord can include a requirement to install them in the dilapidations schedule.

Adjustments to common parts
In a typical shopping mall environment, the tenants, as service providers of the shops within, have duties to provide disabled access to them. The (DDA) provides that a service provider who is a tenant is entitled to make alterations to the premises he occupies under a lease but not, apparently to other parts of the building. The landlord is unlikely to be obliged to effect a barrier free environment; unless he is himself a service provider or a tenant can suitably demonstrate that the service(s) which he is providing is to enable the public to gain access to the shops.