Here are the national websites we like:
ACIE is the Association for Charity Independent Examiners - lots of good support and information
The Charity Finance Group specialises in supporting those managing finances in a charity. They can also help you find your local Community Accountancy Service.
The ICAEW has a whole section specially dedicated to the charity sector
NAVCA is the national voice of local third sector infrastructure in England
NCVO is the National Council for Voluntary Organisations
Humentum is based in Oxford and supports NGO's with financial management here and all over the developing world
The Charity Commission is the starting point for information and guidance for charities
The HMRC charities website is the place for guidance on tax, gift aid and all those lovely things
The Companies House website is the place for companies
The CIC Regulator website is full of information about Community Interest Companies
ACAS is the Advisory, Conciliation and Arbitration Service - lots of good free employment advice, support and information.