Cooleo
Dont want to poor cold water on enthusiasm but you ned to get real on cost I am afraid. The PPL route is still expensive. The NPPL route (SSEA) has hardly made it more affordable. There are one or two clubs such as Seething which offers training at a huge subsidy but you wont find may of them and you will be expected to be there every saturday to clean the toilets and polish the runway with a toothbrush - actually you no longer need to do that last bit but you do have to be there every weekend. Not easy of you dont have transport.
The cheapest route is still NPPL microlight then if you wish convert to SSEA. YOu can upgrade from NPPL to full JAR PPL if you need to.
Microlight schools dont require the samel level of airfield and often have few overheads so can afford to offer training for less and still make a small profit.