As well as Lucking and Beale that Kenton points out there is also some more in :-
Branch Lines around Weymouth V.Mitchell & K.Smith Middleton Press 1989 - 2005(3rd reprint) ISBN 0 906520 65 7 has 15 pages of photos and a useful topology map of the line/sidings
Paddington to Weymouth, D.Phillips, Irwell Press Ltd 2012 ISBN 978-1-906919-29-0 has 10 pages and a 1959 OS map of the area.
I was thinking of an N gauge version as the town bridge to the quay is about 2000ft+ (check google maps with the scale) which could be a manageable 14ft+ uncompressed !