In the end I tried 30second subframes with the gain at two thirds of maximum (Sharpcap setting 400 on gain scale of 1-600) and 2x colour binning.  I took nearly 200 images but discarded around 20 where the bright bit of the comet crossed a star in the field of view.  Even with flats and darks the result was quite noisy and needed smoothing heavily as can be seen in my images.  However they do also clearly show that the new and only bright part (B per Denis's image earleir) is the only clearly identifiable condensation.  In my images it is almost round too - like a normal coma if it was at the front of the comet.

I did also try some 60second images but by then the comet was too low from my location and I ended up blocked by my own roll-off roof.     Afterwards I imaged C/2017 T2 PANSTARRS and I hope to post an image later - it was looking much more healthier!

Peter