Cook bacon until it's crispy.
While the bacon is cooking add onion, clams, celery, chopped potatoes, clam juice, broth, seasonings to crock pot & cook on high 3-4 hours or on low 6-7 hours
When bacon is done - chop & add to soup
During the last hour - add half & half.
In a separate bowl combine cornstarch & milk - add to soup & allow to continue to cook & to thicken
If it's not as thick as you like - add potato flakes 1/2 a cup at a time - waiting about 10 minutes before adding more until you reach the thickness you desire