You
can fly a G-reg aircraft in the UK on a FAA PPL (with some restrictions, of course).
If you're an ab-initio Wannabe, then to fly for a UK airline you have to have, as a minimum, a JAR-FCL CPL/multi-IR with ATPL 'knowledge' (i.e. the frozen ATPL). I'm sure he is wrong about you being welcomed with a FAA licence.
However, there are some small signs that it may not always be a case of JAA or FAA - I think that it has just become easier to convert a FAA IR to a JAA IR, for example. Other changes might follow. Or they might not.
If you can live and work in the USA you could, of course, go down the FAA route and fly there.
(several edits to try and give that ramble a semblence of clarity
)