Please follow the Discretionary Course process which can be downloaded from the portal here. This explains that you need to email your TPD with details of the course, estimated costs and justification for attending the course and justification if it is outside of London. If your TPD approves your request, they should then forward this to the HoS on your behalf for final approval before you complete the discretionary application form. If at any point along the approval process your request is declined you will be emailed to let you know the reason why.