No longer relevant to me as I have moved back to the UK, but my accountant always advised me that a trip was a duty period. So a turnaround began and ended outside the UK therefore didn't count, but if I went to the hotel then that was two trips - one in, one out.
As above, though, the definitive answe is to ask HMRC and get it in writing. As I have previously discovered the hard way, if your acocuntant gets it wrong it is still you that is liable!