Collateral loans - 'simple debts' or chargeable assets

That sounds like a receipe for disaster listening to me. Just an interpretation based on what more knowledgeable types have posted on the subject in relation to other platforms eg SS elsewhere.

Reason for question is that I don't want to find myself in a position where I breach the £44k chargeable asset disposal limit and so should fill in the SA CGT section, and therefore have to provide the calculations which would have to include ABL deals below/at/above par and some amortizing loans (monthly disposals) just to show that no CGT is due!  All this is of course if my understanding is correct.

Whilst you are correct - you should complete the CGT section if the value of your disposals are above the limit, I wouldn't bother if your chargeable gain is below the annual exemption amount.  HMRC can only levy penalties in respect of returns if there is an error on the return or other documents which either understate the tax or misrepresent the tax liability (late filing and payment penalties are addressed seperately).  Penalties themselves are based on a fraction of the potential lost tax revenue.  Therefore were HMRC to find out that you did not complete the CGT section when you should have, you would not be liable to any financial sanction if no tax were due (if tax was due then intentional omission of the CGT information could led to a 30-100% of tax due penalty as the error could be argued as deliberate and concealed).

A good summary of the current penalty regime is give at:  www.rossmartin.co.uk/penalties-a-compliance/223-tax-compliance-new-regime

Bottom line - I would only bother completing the CGT section of the SA form if you have any uncertainty on whether you have any CGT liability.  Otherwise failing to submit the CGT section will not have any real consequence.