Thanks for the reply - the test roll idea is a good one which I'll definitely put into practice.
The scans are a bit hit and miss - what you describe seeing on screen is kind of what I've got on the physical print.
When I print at grade 2 I get lots of lows and highs but no midtones - I've reduced contrast to grade 1/2 (half) (ideally this would be zero) to give me better range of midtones but now I'm only seeing the middle part of the exposure curve (loss of lows and highs). Any small adjustment of contrast filter results in a huge contrast shift when printing. My thinking to give me more control is to reduce the contrast in the negative and give me a more gentle exposure curve with which to print with.