I'm all ok with that but the question I have is this,once the drain plug is undone , does the oil naturally find its way out by gravity or do I need to somehow help it through from the tank to the drain plug?
Surely I can release the pipe from said oil tank and drain oil tank directly aswell as open drain plug?
As mentioned, the majority of the oil is (should be) retained in the oil tank which needs to be drained separately. All that should be in the crankcase is a few ccs. Triumph plunger oil pumps aren't as prone to wet sumping as the gear types fitted (especially) to Nortons.
The advice to clean the gauze is good.