Give Alan a ring and have a chat.... if he doesn't cause you to run for the hills then arrange a first supervision session, which will be free of charge, either in person or by phone, for around 30-60 minutes, according to need.
If you decide to continue, then you will need to arrange a Standing Order to Alan for £25 a month. This will entitle you to one session per month, plus additional access in urgent situations.
This entitlement is well in excess of minimum requirements for most professional bodies (see opposite/below), and you will determine the extent to which you use the arrangement, not only according to how confident you are feeling within your practice, but also with an eye to those requirements
You will need to keep your own record of the sessions, as part of your CPD record, and produce them on demand. How much detail you record is a matter for you, but at least the date, style and duration should be recorded.