As with the vast majority of cities which have developed and expanded over a number of centuries, London has not historically enjoyed the benefits of a coordinated planning policy. Consequently, well designed or adapted buildings are a rarity. However, the Disability Discrimination Act now means that public buildings, at least, will have to make provision for those with disabilities in order to ensure equal access to goods and services.
Some of these legislative requirements also extend to private landlords who provide rental accommodation. The Act prohibits unjustified less favourable treatment if you have a disability and are looking to rent accommodation. For example, landlords must not charge a disabled person a higher rent or deposit than other tenants.
In most cases, you should contact your accommodation office first for information about what might be available.