You do not need planning permission to move internal walls.

Removing a load bearing wall will require building control approval as it is altering the structure of the property. You will be required to provide a report from a structural engineer who will provide structural calculations.

Work on internal walls may also affect fire escape routes, ventilation, drainage or electrics. These should be considered during the design process and work should be carried out by a member of the competent person scheme where possible.

‍

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.

To qualify as permitted development some household building work projects – notably extending a house – must not exceed limits to the volume being added.  

In England, the volume allowance mostly applies to loft conversions. You can read more on the Planning Portal. 

Use the volume calculator to find out the volume of several loft conversion and extension types.

An improvement notice is a notice served by a local authority requiring a property owner to carry out specified works to bring a building into compliance with the legal standards. These are most commonly served to landlords to make a building safe.

The notice will specify what works should be completed and when it should begin and be completed by.

Failure to comply with an improvement notice is a criminal offence.

‍

Yes, but you will need to obtain planning permission. Converting a detached garage into a self-contained living space, such as annexe, studio flat, or retail unit, represents a material change of use, particularly if it will function independently from the main house. This is because the garage would no longer be used in connection with the main dwelling and would effectively become a separate residential unit.