Wide range of RBGE Certificates and Diplomas in botany, plant ID horticulture and allied disciplines some in partnership e.g. Certificate in Practical Horticulture endorsed by Botanic Gardens Conservation International (BGCI) and the RBGE Diploma in Garden History endorsed by the UK Garden History Society.
For more info see RBGE web site for details on all: http://www.rbge.org.uk/education/home