The following organisations are a good source of training:
The National Council for Voluntary Organisations (NCVO)
NCVO champion the voluntary sector by connecting, representing and supporting voluntary organisations. Visit their training bookings for online training on everything from governance to financial planning and check out their studyzone for recorded webinars and pdfs
Directory of Social Change (DSC) and Civil Society UK offer training.
Chartered Institute of Fundraising offer training for members and non members and (free) resources.
Charity Finance Group (CFG) run a wide range of events and training courses.
Power to Change support social enterprise and have a resources page and an events page listing training opportunities.
Locality are a membership organisation supporting community organisations and have a handy resources page with info on everything from governance to marketing.