"basic aid" has been a required training element for a while so should already be being included in training days for u/g to Experienced at least and may have featured in the general marshalling or incident handling areas if not a specific item.
Getting first aid training from a recognised body such as Red Cross or St John would certainly be a worthwhile thing for individuals to do anyway as you never know when you might be able to put it to use in day to day circumstances.
I certainly don't think we need to start going around trying to create whatever people might "think" is needed for the forthcoming "basic first aid" training module that will be required for upgrade to Experienced ..... what it appears we do need though is some idea of what the module will be and how/when it will be delivered.
As Steve Fox says - a basic aid session has been covered at Goodwood marshals training in the past and I know it has also been covered by BARC in theirs (at Thruxton). ...... it is purposefully very, very basic based in my expereince - whether the new "basic first aid" module will be any different and cover different items remains to be seen.
As Richard says - he is working on the first aid module (although I am not sure what the First Marshal On Scene(FMOS) module is to be as this isn't listed as being one you need a signature for in the requirements

.. so I presume it is actually a sub-module

)
Finally, to go back to a point from the original post about "need training days over 2 days" - remember that training signatures are limited to one training day per calendar year (ie 2 days = 2 years).
Dave