After some encouragement I decided to add Startools to the arsenal.
It has taken 5 days (on & off) getting up to speed with it, and I have to say I found it very good.
Ivo, if you read this 'thanks mate, a bloody good piece of work!
I did however use Pixinsight for batch pre processing and pixel math to add the Ha
Once again, thankyou for honest appraisal, esp. Marc & Mike
L 50x5m RGB 30X5m Ha 30x5m
https://www.astrobin.com/full/e2iyun/0/?mod=&real=