@Derek613 I cannot help but I can sympathise. The situation you are in is complex and doesn't seem to fit well with HMRCs standards.
We have struggled for years to get the correct tax and National Insurance treatment and basically go through the same angst every year when trying to pay voluntary NI. It does not help that I keep forgetting what we have been told!
The key though is to call HMRC at 8.30am when you should get through in minutes not hours.
Tax is really quite easy as we just answer questions on the tax form until we get the right tax outcome (I am sure this is not the way to do it). Basically we don't go for self employed but do say the income is from property and as we are a Furnished Holiday Let we get the benefit of the money being profitable. Also we pay the lower class of voluntary NI that only costs £160ish per year.
The last Government did look to take away the FHL benefits though and I don't know where they got to or how it applies in Scotland.