How do you anticipate finding out if your source is safe? Two ways I'd go about it are to 1) Go watch them milk. See how well they clean the animals and their equipment. 2) Make cheese with the raw milk and see if your cheese "blows" (it'll start swelling and the interior will be filled with tiny holes, kind of like it's been shot with a shotgun). This will tell you coliform bacteria are present. Most coliform bacteria are harmless, but of course e. coli is not. It is the fact that coliform is present that tells you something is amiss. This doesn't say anything for listeria, or brucellosis, but looking at general herd health is where I'd begin.
I'd love to hear suggestions from others on the topic.
Pasteurizing (145° f for 30 minutes) should not affect curd formation. Thermalizing would be less so, but IMO, is not a safe option if disease is in fact present. As Salty answered, just take it down to the recipes temperature.
