Thank you for confirming.
I understand that you have been married since January 2007 and that you lived with your wife in the UK since then. You have now separated.
You should know that under EU law you retain your right to residence in the UK even if you are separated from your wife, provided that your wife remains in the UK.
Once you have obtained a divorce, under EU law, as a former non-EU spouse of an EU citizen who was exercising her rights to free movement, you have a right to remain in the UK because you have been married for more than 3 years and you lived in the UK for more than a year.
You would also have a right to remain in the UK if you were granted parental responsibility over your daughter by a court or by agreement with your spouse.
At this stage, you do not need to do anything, but you should consider starting divorce proceedings. You may also want to see if you can get your wife to agree to a parental responsibility agreement that sets out your right to access to your daughter.
Once you are divorced, you would need to contact the Home Office with a copy of your divorce order. You will need to prove that your wife was living as a self-sufficient person prior to your separation by providing proof of your income, proof that you provided for your wife (eg your paid the rent and family living costs) and proof of healthcare insurance. It would also be good if you could get a copy of your wife's passport.
I hope this answers your question.