With respect to Ghengis, if its the most economic way to get a license that you want, then NPPL M followed by conversion to NPPL A is the way to go.
These days most three axis training is carried out on either the Eurostar or the CR42, both of which may be registered either as a microlight or as group A. If you happen to build a bit of post license issue experience on a similar type then transition to spamcans is really not difficult.
Finance-wise, one is looking at 25 x £125/hr or so plus whatever extra you need to get through it. I was put forward for my test in minimum hours, and depending on how you apply yourself, you may be able to also. A previous obsession with aeromodelling or flight sims certainly helps here.
To convert to group A you will need two hours of stall/spin awareness training and an hour of instrument flight appreciation. You can then take a navigation flight test and general flight test.
This is easily the cheapest way to get into the left hand seat of a group A aeroplane. I believe the training on different types to be of benefit if you have a significant aptitude for flying as you will become a more rounded pilot. If you're rubbish then sticking to the same type and the same instructor is always better.