Points leader Ilya Mikhalchik picked up where he left off last time out as he led the way in FP1 with a best lap of 53.162secs.
In a session delayed after track contamination sparked a big clean up, Mikhalchik finally finished 0.137secs ahead of rival Luke Mossey.
Josh Owens was third quickest, with Declan Connell fourth and Finley Arscott fifth.
Pirelli National Superstock Championship, FP1:
1. Ilya Mikhalchik (ROKiT BMW Motorrad) 53.162s
2. Luke Mossey (Milenco by Padgetts Motorcycles) +0.137s
3. Josh Owens (SAF Holland Honda) +0.667s
4. Declan Connell (B&D Roofing Racing with WSC Performance) +1.121s
5. Finley Arscott (SAF Holland Honda) +1.137s