In the same way that Wikipedia has more articles on popular culture than neuroscience, OpenStreetMap has much more detailed data in places like central London and tourist honeypots than most suburban or rural areas. Most roads are covered in the UK, however. You can find more information about completeness of the mapping in your area on the OpenStreetMap wiki page on completeness.
You will need to decide how much you want to prioritise adding detailed information to your local area versus filling in gaps in the surrounding area. There’s not much point recording the position of every house number on your street if useful routes to neighbouring areas are not recorded.
At a starting point you should ensure the following are recorded within the surrounding five miles:
- roads, including names (so that people can use journey planners)
- bus routes that operate at least daily (note all bus stops are already marked)
- rights of way plus walking and cycle routes that have direction signs (such as long distances paths and national cycle network)
Once that is done, consider adding:
- traffic signals, crossings and mini-roundabouts
- speed limits and traffic orders, such as one-way streets
- car parks and secure cycle parking, cycle shops and hire
- key ‘Points of Interest’ such as schools
- large buildings and land types such as woodland, as these help people navigate
- the presence of footways by the side of roads outside urban areas
- surface conditions of useful rights of way and obstructions such as gates and stiles
Again the ITO map visualisations show different versions of maps highlighting particular information such as surfaces as well as highlighting potential errors in the base data.