While there are no orders or plans in place, you can do as you please in terms of parenting, so yes, you can just go and pick her up.
Will there be repercussions if it ends up in court? It's impossible to tell without knowing all the details, but how you conduct yourself from this point forward is important. To that end, here are some things you might consider if it were to reach court (let's hope it doesn't).
First, a court will listen to the views of a 14yo child, so if she were to tell a presiding magistrate or judge that she wanted to live with you, it would significantly influence he outcome.
Second, courts do not look highly on parents who are unwilling to facilitate a child's relationship with the non-primary carer. For your ex, this probably isn't good news, but for you, it means that if you do collect your daughter, you must still enable your daughter to contact and spend time with her mother. You don't have to force her, but just don't discourage her. I would also wager that if your daughter fears the mother might just not let her leave during a visit, then phone contact would suffice.
Third, before you act, consider whether you are able to ensure your daughter's needs are met. Is she able to attend the same school? Are you able to get her to school? Will she have her own room? Will she still be close or able to contact her extended family? Can you afford to have her? All of these things would be addressed in court so make sure you are positioned as acting in your daughter's best interests.
If you act, the mother may apply for a recovery order, but without any parenting or consent orders, there is not much the police can do.
The mother may also pursue the matter through court, but she would have to mediate with you first anyway.
I hope this is of some assistance. Good luck.
