Generally, you will need permission for any works (building, demolition, alteration) on land or buildings and the making of a significant change of use of land or buildings unless you are working on an exempted development.
If you are hoping to build a house, you will definitely need planning permission. If you are just going to build an extension or make certain changes to your existing dwelling then you may be exempt as some small extensions and conservatories don’t require permission.
Guidelines can vary slightly from county to county so it is best to check with your local authority. They will also be able to tell you whether or not your plans are likely to comply with their guidelines before you go to any additional expense lodging the application.
Although most people are familiar with the standard planning permission there are actually three types: permission, outline permission and permission consequent on outline permission. Outline permission requires you to produce only the plans and particulars that are necessary to enable the planning authority to make a decision in relation to the siting, layout or other proposals for development.
If you get outline permission, you will have to submit detailed drawings and receive consequent permission before you start building work. Generally, outline permissions have a 3-year duration.
It is an offence to carry out any work that requires planning permission, without the correct approval and you can be heavily fined or even imprisoned if you are found to be in breach. While it is possible to apply for permission to retain an unauthorised development this can be refused and the structure will have to be demolished.
If you are in a hurry to complete your project you should be aware that generally, the local planning authority must make a decision on a planning application within eight weeks of receiving the application, but if they need more information, or the decision is appealed, it can take much longer so allow for this in your timeframe.