You'll need to register with a different practice first, especially if you met her as a patient during a consultation. To do this, you should either go to a different practice and ask to register with them (however, they may be unhappy to take you if you are already with a neighbouring practice and may ask for a valid reason – usually a breakdown in the patient/doctor relationship or if the rest of your family are with the "other" practice and you all wish to be registered with the same Doctor) or you will need to contact your PCT (if you are in England) or LHB (if you are in Wales) and ask them to allocate you an alternative GP. It's not that uncommon for Doctors to be the (unwanted) recipients of patients' attractions and it's likely to be rejected, having been met with suspicion, if approached in the professional setting.