This is not really all that hard to do. There are companies and agents that will help a band and a composer with copyright permissions. I have done it for band pieces, marching band, drum corps, and a brass quintet piece. They were all easy as the company I hired did the work
The tough story:
I had a kind of obscure church book I used to make into a play and used public domain hymns for the music and the congregation was invited to join on some of them. Others hymns I completely changed the words. Anyway, I wrote the author, he referred me to the publishing company, they referred me a company that handles their copyrights. It took about 3+ months and about 8 letters.
All in All, I was expected to pay the going rate of buying a church musical for kids -- about $250 to $350. They finally sent me permission for FREE! All I had to do was have at least one book on display for the congregation to look at and write an acknowledgement of thanks in the Bulletin/Program to the company and author (which any would do anyway).
I went to Barnes and Noble (a big book chain store in the US -- see
www.bn.com). They let me order 20 books and if I did not sell them, I could return them. I think I sold 15 and returned 3. I kept 2 incase someone later wanted one. I sold both of them the next Sunday and could have sold at least 10 more. I those who wanted a copy when I had run out to BN.com.
There are at least 3 companies (in the US) that for a small fee will secure you copyright for you. I am sure a company in the UK or the EU will do the same. You should be able to find them with a good internet search.