Mr John Penny MA of the Fishponds Local History Society has done a study of the Luftwaffe over the Bristol area 1940-1944 and has detailed the German losses over the Bristol area on the following site:-
http://fishponds.org.uk/luftbri11.html. This may be of assistance to you.
There used to be a web site which had a record of all aircraft accidents in Gloucestershire
http://www.rcawsey.fsnet.co.uk/glos1.htm but it appears to be dead at present.