The official version of the rules for the British Go Championship, the British Pair Go Championship and the British Youth Championships is the BGA Championships Rules [1] page.
The BGA underwrites the costs of running the above championship events, including prizes, using sponsorship money when possible. Entry fees will be set at a realistic level.
The system of qualifying as BGA representative at various overseas championships is described in the BGA Championships Rules [2]. The BGA web site holds Lists of past BGA representatives at international tournaments [3], and describes the entry criteria for each international tournament to which we send representatives.
The BGA will not normally pay the expenses of those representing us overseas.
Links:
[1] http://www.britgo.org/bchamp/chrules.html
[2] http://www.britgo.org/bchamp/chrules.html#h
[3] http://www.britgo.org/reps