Since my posting yesterday I have checked my documentation and you do not have to obtain a UK RT Licence. Your national licence is acceptable. What you are looking for is an English language competency standard in line with ICAO standard Level 4. You will be able to do this at an approved English language school in Denmark. Your national licensing authority will be able to give you the names and addreses of approved centres. My own experience is that most Scandinavean pilots speak better English than many natives.