Why do you need a ‘controller’. to do a practice RNAV approach in good weather? There is no ground equipment to switch on or monitor, and Shoreham is in uncontrolled airspace. Just fly the approach track and altitudes as a visual approach.
Shows what’s wrong with Luddite restrictions in the UK. In the USA and Australia for example, RNAV approaches are routinely carried out IFR/IMC with Unicom only.