In Britain, local authorities are the creation of Parliament - who can reorganise or abolish any of them. Unlike the states of the United States - they have no independent existence. Even the right for a community to call itself a "City" is dependent upon the Royal Prerogative.
The last major reorganisation took place in 1974. For most of England there was a two tier structure - with county and district levels. The metropolitan Counties were abolished - after resisting the policies of the Government in the 1980s. Some other authorities were given unitary status - combining and replacing county and district functions.
Milton Keynes is a unitary council. They have an extensive website accessible here. Citizens can access details of Cabinet and Council meetings - and read the reports which will be considered. Other documents relating to the council are available here. The Council is made up of 51 Councillors, elected for four years - with a third facing election each year (with 2013 being an election free year). The current list of councillors, listed by party, is available here.
The area is also served by a number of Parish Councils. I live in Furzton, which is in the south west of Milton Keynes city (the whole district includes rural areas to the north and east). We are served by Shenley Brook End & Tattenhoe parish council. Despite the name - this has nothing to do with church parishes - but is a local authority providing some vital services at a community level. For more details of parish councils in Milton Keynes press here.