I ride this route often on my way to other areas, road after Bridge end and close to the forty foot drain area suffering subsidence so 40 limit in place, scenery isn't awe inspiring but I am local so this maybe unfair (although the wind turbines still seem to have an hypnotic affect). A52 from Grantham is OK but covered with average speed cameras (high accident rate) - I would suggest heading south from Grantham and riding the A151.
Another nice Lincs road, especially at weekends when less HGV traffic. Some great straights, nice bends, mainly sweeping but a few sharper. Section west of A15 is my favourite - very few villages mean that good speeds possible which may be why there is sometimes a mobile speed camera.