From the Charity Commission's website:
"Many people starting a charity assume they need to register with us, or think that a registered charity number is necessary to carry out voluntary work. However, in the UK today there are probably over 500,000 voluntary organisations but fewer than 180,000 of these are registered charities.
Applying to register a charity is a complex process, and we don't want to waste your time if it's not necessary for you to do so"
Source:
http://www.charity-co...of_charity_index.aspx
The policy of the Charity Commission is not to register charities with an annual income of less than £5000. However the Commission still provides advice to such charities:
http://www.charity-co..._small_charities.aspx
(If the income rises above £5000p.a. the relevant link from that page provides further information).
Chris