The order has the effect of eliminating the need to apply to the local authority for planning clearance for a change of use from office to residential. However, even if a development is "permitted," it does not eliminate the need for consultation with the local government. Planning clearance may be needed for construction activities such as digging up roads or placing fill on land. In general, no special permission is required to convert an office building into residential apartments. There may be restrictions on when you can do this (for example, if you want to make changes to the building's exterior), but otherwise, the procedure should be straightforward. It's important to check with your local government body about whether any additional permissions are required before you start work. If you already have planning permission for your office building and just want to change its use, then you don't need further permission from your local council. They will usually accept applications from existing licensees so there should be no delay in granting consent. You should check with your local council if there are any special requirements for converting offices to residences. For example, if you intend to put bedrooms in former meeting rooms or space above shops then they may require you to get special permission. But overall, conversion of offices to residences is quite a common thing to do and shouldn't cause problems for most applicants.