I would like to suggest a whole DLC covering the section of the Great Eastern Main Line between Ipswich and Norwich, as well as the lines from Ipswich to Cambridge and Peterborough.
ATS have some in fact most of this either released or as a work in progress. Their updated "GEMMA" line from Liverpool Street to Ipswich is out and the extension to Norwich is being made. Kings Cross to Kings Lynn and Cambridge to Peterborough are available and the link between Ipswich and Cambridge is also a work in progress.
