what are the prospects of employment after gaining a ppl (I do realise by the way that I would have to do IR and cpl etc...) IE is it a worthwhile investment with regards to starting a career in aviation (with regards to maybe sponsorship or securing a personal development loan).
I'm not really the one to answer this, but I have heard it said that if you are in your twenties, with determination, perseverance and the requisite talent, then the chances are that you should be able to get some kind of job flying eventually. If you are older then it is a significantly greater gamble.
In the current climate it is probable that you will have to pay for all your fATPL (CPL/IR + ATPL theory). There are a few schemes that can help, so it is worth doing some research, but sponsorship to take you from 0 to an fATPL is very rare and keenly contested. In general I would have thought that a PPL would help with (or, at least, not hinder) applications for sponsorship towards the further licences and ratings. As for CDLs, they are intended for vocational training (i.e. skills leading to a job) and so can be used to pay for professional training (however, they are capped at £8000 so will not pay for all of it). A PPL can't really be claimed as vocational, so you would need one before applying for a CDL.
Could you explain the modular route etc...
In an integrated scheme, you go to a training company, hand over £60k (or more) and walk away a year later with a fATPL. In the modular route you organise the training yourself; a PPL here, written exams there etc. You end up with the same licence at the end of it all (a CPL/IR with ATPL theory), and the modular route is usually considerably cheaper (£40k or thereabouts).