Hopefully someone with more experience can chime in since I've never actually made it but if it will be kept warm for several hours you may want to use fresh cauliflower and not even precook it so it doesn't get super mushy sitting in the crock pot(depending on how big you cut the florets).  I've never actually used cauliflower in a crock pot but standard cooking it doesn't take that much time to cook or overcook.  If you go this route you may want to add a couple extra tablespoons of cream to give it a little more liquid to cook the cauliflower in and then leave it on high until almost done and turning it to warm to slowly finish off the cooking.  

Personally I would probably just run a test batch if at all possible before trying it out at work.