wrote:
Are there any changes of train needed between Euston and St Pancress
on the tube and how easy is it to use the bus between these two
stations and also please can anyone tell me the walking distance
between the two ? .
Try using the Transport for London journey planner.
http://journeyplanner.tfl.gov.uk/

Use 'Euston' and 'Kings Cross and St Pancras' as the start and end stations.

The journey planner reckons it is 17 minutes to walk between them.
One stop on the Tube.