I did the FCE course at Ability, which lasts for three months to prepare you for the Cambridge exam, and it did a great deal for me with regards to improving my English.
Different from the General English classes the FCE course begins and finishes with the same students, which is very good to meet people and make friends. Also because it is an academic course you have plenty of activities to develop yours skills in listening, reading, writing and speaking in English.
For me, it was a great opportunity to clean up any or all mistakes in my English (mainly on grammar) and it also helped with increasing my vocabulary.
I made lots of good friends and I was definitely prepared for the test.