I dont necessarily think that the training you would receive in the USA or elsewhere for your PPL would be worse, however, I do feel that if you plan to fly in the UK, training in the UK is better.. for a start you will be learning in the conditions you will be flying in normally... and UK training is certainly better suited to flying in the UK.
Most people that I have come across returning from the USA with a PPL have required around 10 hours of extra training to get them up to scratch flying here. With some there were major deficiences in almost every area, others it was just a case of getting used to the more congested and cluttered UK airspace, navigating here (the scenery is obviously rather different), R/T to name a few.
Even the best will require a good few hours to convert once returning. Also once you factor in travel, accomodation and food etc, the USA really is not a lot cheaper in the long run.
There are also a good few flying clubs/schools in the UK that do not cost the earth and also in my experience, in the UK at least, the price that a flying club/school charges has very little relation to quality of training provided.
Since you are planning to go on and do your CPL etc you need to take in to account a few factors which might help you in the long run.
I think it might suit you to do your PPL in the UK, possibly somewhere fairly busy so that you are prepared for higher workloads and busier R/T conditions.
With regards to hour building, I would try to do this as cheaply as you can (so by all means go to the USA, South Africa, Canada etc etc) however try to make every hour count, get your IMC+night, do a complex conversion, do try some longer nav routes, and go up with an instructor every 10 or so hours to iron out any bad habits that may be developing. But make those hours count, it will help you through the CPL and save you money in the long run.
If you want to hour build in the UK, the hiring rate from most flying clubs generally makes it expensive, so consider either buying into a group if you have the capital, or join a non-capital group (ie where u just pay per hour, or monthly and per hour). You could consider approaching a flying club/school and negotiating a favourable rate for a block of hours (most flying schools do not have all of their aircraft busy all of the time) or even private owners.
I dont think it makes a jot of difference where you do your PPL with regards to future employment. CPL maybe, but thats a matter of opinion
Even if you do decide to opt for an integrated CPL course, I would still do a PPL first, it will make the CPL course easier, whether modular or integrated and also if in the slim chance you find flying isnt for you, you wont have blown £50k getting there.
These are just my opinions, they;r enot set n stone and I'm sure some people may agree and some will disagree, ultimatle u have to go with your gut feeling.
Sorry if this had been a bit long winded
PM me if you want any more info/advice etc
LP
(edited for those nasty keyboard and spelling gremlins)