This is a community stadium which is clearly shared with the local athletics club. I also am not 100% that it is indeed the home of Grantham town!! Whilst searching in the town this is what I found and a decent enough ground it is too.
Main stand on one side with areas of terracing next to it and a terraced stand opposite. Not much behind each goal.

Lady Thatcher took the title of "Lady Thatcher of Kesteven" having been born and bred in Grantham.

click picture to enlarge