If you need to stay overnight while attending your course, it is best to stay in the northern area of Lincoln, to minimise traffic delays in the mornings.
Here are a few that previous students have recommended:

Search on airbnb for places to stay in or near Sudbrooke LN2 2FD

Also, try these:

Langdale Lakes B&B  Lovely, peaceful location a couple of miles from the course

Haymans Ghyll  B&B   (very close, in Nettleham village, highly recommended by our students)

The Old Vic Self Catering cottage  (very close, in Nettleham village, highly recommended, self-catrering - good for longer courses) 

Good Lane B&B        

The Lincoln Hotel  

The Allotment House