Championship leader Filip Surowiak held off Ethan Sparks to end the opening BTC session on top by 0.059secs.
Aboard his City Lifting Team Honda, Surowiak set a best lap of 1min 39.821secs, the fastest lap of the session, as Sparks was second quickest at the flag.
Ryan Frost was third for the Fibretec Honda by Mlav Racing squad, with George Bowes fourth and Harrison Mackay fifth.
R&G British Talent Cup, FP1:
1. Filip Surowiak (City Lifting Team) 1min 39.821s
2. Ethan Sparks (Kovara Projects/RS Racing) +0.059s
3. Ryan Frost (Fibretec Honda by Mlav Racing) +0.770s
4. George Bowes (GB|67/Edwards Racing) +0.823s
5. Harrison Mackay (Kovara Projects/RS Racing) +0.876s