Lac Du Tard
Route du Norrois
The Best way to get to the lake is to drive from Calais (ferry or eurotunnel). Once you get off the ferry head to A26, when you get on the A26 continue all the way to Reims, this is a good 2 hours 30 min and the bulk of the drive.
Take A26 to D21 in La Veuve. Take exit 27-La Veuve from A4/E50
Take N44 and N4 to Lac Du Tard
The co ordinates are 48.682994, 4.641039. You can copy and paste this straight into google maps for directions from your front door. This will bring you out to the gates of the lake.
Total Drive from Calais is about 3 hours (non stop)