If you fly for fun only then you will need a Class 2 certificate. There is now the option of getting a private pilots licence with a DL9 certificate. This is cheaper, and can be done by your GP. See information from CAA by clicking here . This  link  from CAA provides advice about the different privileges

If you intend to get an Instrument Rating then you will need an audiogram as well; otherwise this is not normally required unless you have hearing problems. Skydive Instructors also need to get a Class 2 certificate (audiogram not required)

​Initial  - requires an application, examination, bloods, spirometry, and ECG
Renewal - application, and examination but other tests may be required (see timing of these here)

​Applying for a Medical Certificate

I encourage pilots to apply for their medical certificate on line using Skycert as this is more secure, faster, and easier for pilots. See details here. The URL is How To Get Your First Medical With SkyCert