421C there are bigger things to sort out in the UK in flight instruction apart from technology.
They can't get ex 1-13 and stalling taught properly.
Your job for PPL is to teach basic flying skills. Anything above the basics is for post qualification.
Alot of PPL have learned to just play dumb with instructors just to get through check rides. Claim they don't know how to do the subjects which have the most variation between instructors and see how this one likes to do it.
To be able to progress onto technology you have to have a foundation in the basics. Currently there are folk out there that can't fly straight and level in trim.
Currently there is no room in the PPL to do any extra without missing the basics out.
An 8th subject in the theory I wouldn't object to. But know there would be much nashing of teeth and complaints if they tried to bring it in.