Not offending you, but first he was not UK, he was Austrian, the MCC provider was a reputable MCC provider, but was not accepted by his CAA!
Sometimes, and people should be aware, that it can be quite a bit extra paperwork involved when using unusual providers, from foreign countries, one of the issues is the verification process of all documents to the FTO.
I know probably not end of the day, but unless there is a significant saving in costs, I would not take the chance for this! Also you have another issue, ATPL theory must be completed in the country where you do your CPL/IR, unless you get special permission in advance!
Knowing how some countries English level is on the ATPL theory questions, I would also avoid doing this abroad, so if you do ATPL in UK, you can not automatically do your training in Serbia!
There are so minimal savings in doing this, if any at all!
With a well known provider in the UK, you can do CPL/MEIR the flying part for £22.000 - £23.000, if you do minimum hours. That gives you around 22 hours ME with a DA42, and CPL in a SEP!
I doubt very much you would be able to offer a program for the above, showing you significant savings on this!
Than include the hassle to have to do your ATPL's in Serbia!
Than you will have companies not recognising this school when you go for an interview! Hmm. sorry, not me preferred choice, not saying it is bad, but I would never have considered, even if I saved £500 - £1000!