When you see a private doctor they will issue you with a private prescription for any medication that they recommend that you take. 

A prescription is a legal document which a doctor signs, either electronically or by hand.

Whilst NHS prescriptions are either free or subject to a fixed prescription charge, private prescriptions vary in cost. The cost of a private script is entirely borne by you, and the fee is made up of the cost of the medicine plus the pharmacists charge for supplying it. The pharmacist will be able to issue you with a receipt for your prescription if you need it to claim from insurance.

Private GPs are not able to issue an NHS prescription. NHS GPs can issue either private prescriptions or NHS prescriptions.

Controlled drugs are drugs that are subject to high levels of regulation. The government determines which drugs are classified as controlled drugs - typically this classification relates to drugs that are especially addictive and harmful.

At Mayfield Clinic, only in exceptional circumstances would we prescribe controlled drugs, and most likely only to long-standing members of the clinic with whom we have an ongoing clinician-patient relationship.