SI are what're taught in UK schools for all those such formulae so I'd be very surprised if they ever expected much more than passing familiarity with imperial in tests (my asst tests were also SI).
They might however use such units in questions where it doesn't actually matter, just to see if you're thrown by it. Ie both qn and answer are in the same units & hence no conversions required. Could always ask Cabair themselves.
Good luck. BM