Agree about the George at Leadenham. RamJam, as is said is good, big comfy armchairs, settee etc.
Betweeh Coningsby and Woodhall Spa is the Blue Bell but do duck. It is like the Black Horse at Greetham used to be (not been in for many years) tiny with lots of signatures etc on the ceiling.
Then there is the Petwood Hotel at Woodhall Spa, look in the Dambuster's Bar. Even if shut they will open that bar for you.