The power to hold raffles where the tickets can be sold prior to, and not at the location of, a fund raising event, comes from:
Gambling Act 2005
Section 98: Lottery operating licences
(1) A lottery operating licence may be issued only to—
(a) a non-commercial society,
(b) a local authority, or
(c) a person proposing to act as external lottery manager on behalf of a non-commercial society or a local authority.
(2) A lottery operating licence may authorise—
(a) promotion generally or only specified promoting activities;
(b) the promotion of lotteries generally or only the promotion of lotteries of a specified kind or in specified circumstances;
(c) action as an external lottery manager (in which case it is known as a “lottery manager’s operating licence”).
A copy of the Parish Council’s Lottery Operating Licence can be found here