I live about two miles from Ebbsfleet so if anyone has any questions about the local area, I’ll try and help.
Am I right in thinking train station nearby and easy accessible from Euston ?
If so not bad journey to go to watch the linnets 
Yes it's really easy to get to on the train. There's an excellent connection from St Pancras to Ebbsfleet station - there's a train every 15 minutes and the journey takes less than 20 minutes. From Ebbsfleet station I would say it's a 10-15 minute walk to the ground, or there are very regular buses instead if someone can't walk that far.
So from Lynn it's just straight down to Kings Cross, then walk across the road to St Pancras, wait a maximum of 15 minutes, then less than 20 minutes on the train, then 10-15 minute walk.
From Euston it's the same except the walk from Euston to St Pancras takes about 10-15 minutes (or 2 minutes in a cab).