Yes, in most cases you can use an outbuilding as a home office without needing planning permission. As long as the use remains incidental to the main dwelling it is still considered part of your domestic residential use.
Planning permission is not required for internal changes such as changing a bathroom to an accessible wetroom, however, if you live in a listed building, you will have to apply for listed building consent for any significant works, whether internal or external.
Building regulations approval will likely be required for changes to a make a bathroom accessible, specifically when the change will impact the structure of the room, drainage and electrical systems. It is recommended to have work completed by a member of the competent person scheme.
The principal elevation is the most visible or prominent side of a structure, typically facing a street or public area. While often considered the 'front' of the building, it may not always contain the main entrance. There can only be one principal elevation of a house.
In most cases, yes - planning permission is required to operate a business from your garage. This is because the use would no longer be purely domestic, and the garage would be considered to have changed use from residential (Class C3) to a business-related use, which requires planning consent.
Verandas will often require planning permission as they do not fall under permitted development rights. If the veranda is raised over 0.3 metres, covers more than 50% of the land around your house, is on the principal elevation or on a roof then it will need planning permission.
You may require additional consents if you live in a Conservation Area or listed building. If you are unsure, you should contact your local planning authority.
For more information about planning permission for verandas and balconies, read our common project.
Adding a permanent wheelchair ramp for access to a home is likely to require planning permission as it will permanently change the external appearance of the front of the house. If the application is solely for improving disable access to the building then the planning application will be exempt from a planning fee.
If you live in a listed building, you will have to apply for listed building consent for any significant works, whether internal or external.
All permanent wheelchair ramps must comply with Approved Document M of the building regulations which specifies the gradient, width and surfaces which should be used.