Structured hours building?
For what it's worth and based on my own experience, self-improver unstructured hours builder and ME/IR instructor 3000 hours:
IF you know yourself to be abnormally disciplined in your approach to training and you feel you have all the insight needed in to what the CPL requires (not just familiar with Standards Document 3, although it's a good start), then yes you could be one of the few ones I see that will sail through the CPL in minimum hours and first time pass.
But it is more likely - and I don't know the variables such as your age, currently employed? free time? etc - that someone who has done unstructured hours building will have allowed their core skills to at best stagnate, in some cases we find they have fallen to below those that they evidently must have displayed for their PPL test. It's human nature as much as anything! Ask yourself why it is that many employers prefer the Integrated route in any event and then ask yourself if you should allow a possibly negative issue to come up in your job interview i.e. doing your own thing, esp if allied to less than first-time passes. Now if you're up for one of those jobs where the boss is one of those very individual characters who likes similarly-minded employees, then fine.
We run a Structured Hours Building Programme in our Modular training, which includes 19 hours of DUAL flight logged as P/uT. The view is that the student cannot be expected to practise solo to a standard, especially towards the end of this phase, that's pretty close to CPL standard, if he/she is not monitored for maintaining and then improving standards. Remember the CPL course is really quite a tightly-packed one, especially when, as is now the norm, it includes the MEP training and test on the twin. In reality in the 28 hour course, the student has only 20 hours to reach a test standard, with the 8 (and often more) needed to convert on to a new type and class and not lose the test skill standard just reached.
So like others I don't know what this £1500 includes exactly but put it in to the perspective above and I can tell you that unstructured hours builders, especially the more 'mature' ones, generally take 5-10 hours more on their CPL. How much will that cost? NB generally not always.
PS/ As our SHB programme is recognised by the CAA, then the progress checks flown dual ARE counted as P1/S towards the solo total, providing the instructor grades the flight satisfactory and countersigns the log book. This P1/S time usually 8 hours can be counted along with the successful passing of the PPL, CPL and IR tests. Is this the case where you are looking?
Just some thoughts, no doubt they will get rubbished.