Unless you are a native English speaking person from a country where English is the first language, you will need to pass an ICAO Aviation English examination at Level 4 - 6, in order to apply for an EASA licence.
Obviously, your English is good enough to pass at Level 6 but I have assessed many fluent English speaking pilots at Level 6; in practical terms the test was quite unnecessary but had to be undertaken as they were not native English speakers and you need to produce a certificate of test when applying for the licence. The test must also be taken at an approved test centre and using an approved test.
The radio licence is a peculiarity of the UK, and is a requirement of UK telecommunications legislation and not aviation legislation. It just happens to have been placed under the control of the responsible regulatory authority for the transport service covered, e.g. the CAA look after aviation radio licences.
Your FAA licence is not convertible into a UK FRTOL (Flight Radio Telephony Operators Licence. As I remember it, FCC Form 605 permits operation of radio equipment when flying on a FAA licence in foreign airspace only.
If you are not applying for a UK licence you can forget the RT licence but you will need the English language certificate. Sorry, I don't do them any longer, otherwise I could have helped out; but I can point you in the direction of a couple of approved UK test providers,
Mayflower College, Plymouth - English language courses in England and
www.anglo-continental.com.
Hope that helps a little.