Custodial Rights to taking my child out of the country

I am a mother who was granted legal custody of my daughter & maintained this for 13 years in the UK. She & her father wanted to see how life would be like living with him and I granted them this without any court amendment. After a period of settlement, I moved to Cyprus and have been residing there for 16 months now. Since leaving my daughter in my ex-husbands care and I have found out that she has been drinking alcohol, smoking, self harming and has taken an overdose of which my ex-husbands attitude to this behaviour is negative. They constantly argue and I feel that my daughter is a very unhappy teenager. Both myself and my daughter have discussed this matter and we both want her to move out to Cyprus to get her life back on track. I am prepared to enroll her into private education at no cost to my ex-husband and want to spend as much time and effort that is needed to get my daughters life back into a happy state. I don't know what rights I have or whether I have a case. The last thing I want to do is disappoint my daughter. My husband is prepared to fight against me on this matter. Please can you offer your advice?

A tough case which is certainly beyond the scope and depth of this forum. I have no other advice than to retain an expert attorney.