Hi Lucy.
A few years back, I run the Autoglym training school at Autoglym HQ. We would always keep details of trained valeters for such requests. If you contact Autoglym HQ, (at Letchworth, Hertfordshire) they, or their sales person in your area should be able to suggest someone to you.
Autoglym Head Office 01462 677766
Regards.
Paul.