Does my house have to be accessible?

Hello.

Just a quick question I have recently moved to a lovely apartment we have a lovely residents only garden but cannot use it as I have mobility problems and struggle with steps and the garden has loads if you want to go to the other end you either have to climb steps or walk to one of the other blocks and ask security to let you in as the garden is in quad with the other blocks surrounding this is this ok or is this against the law and they should be providing level access as its a right pain.