There are two levels of planning permission, namely full (also referred to as “detailed”) and outline permission (OPP). Outline permission, as you suggest, establishes the principle that a house can be built on a plot. However, since August 2006, rather more detail has to go into an outline application than used to be the case in the past. Nowadays an outline application must include a rough layout plan, an indication of the point of access and an indication of the maximum and minimum sizes of house/garage to be fitted on the plot. These additional details are actually quite helpful if you’re buying a plot with outline permission as they give better idea of what the council expects to see on the plot. This still leaves the finer points of the design – the internal room layouts, external appearance, materials and so on – to be determined later. If you buy with outline permission but want to build something different to what is permitted, you would have to start again with a new, full application. However, if you want to build in line with the general parameters of the outline, you can apply for something called “approval of reserved matters”. This confines the application to those matters not covered by the outline permission.