ex_matelot,
You are certainly not too old to do what you want to - plenty of people have changed career to professional flying at even more advanced ages!
You may find some of the material you have to learn for the various qualifications a bit daunting if you have been out of the way of study for a while. But much of the PPL material is very practical and you may find that you cope well with it.
I would say that PPL is mostly no more than GCSE level, with the possible exceptions of Air Law and Met.
Regarding hours building - there is no way that a PPL can fly for hire or reward, that is very clear. Even if you do not get paid, the task (e.g. banner towing) would still be considered "Aerial Work" and a PPL cannot do it.
You might be able to join a gliding club that operates tug aircraft and get experience that way - but you would have to get at least silver C in gliding first, so it doesn't really solve the problem, plus there are many people competing for a few tug jobs.
Probably the cheapest way to build hours is to go abroad - USA, S. Africa etc. - where hire is much less.
Alternatively, look to join a group with a share in a modest aircraft - it still isn't free, but less than hiring.
You can also investigate flying microlight or ultralight aircraft, which I believe can be a good deal cheaper (Genghis...?)
Finally, you may want to research the BCPL - basic commercial licence - which would allow you to do aerial work while still working towards a full CPL with IR etc. - assuming you want to fly for a living.
HTH
SD