Land may be subject to restrictions on development or use.
Examples include covenants in title documents for the land (enforceable terms between parties) that restrict development or use. There may also be rights of way across the land.
Engage professional advisers who will be able to look into and advise you further as to whether or not such considerations apply to the land relevant to your scheme.
Useful references and links
Royal Institution of Chartered Surveyors www.ricsfirms.com