I had forgotten that only the published examples are listed in Roud. Matthew has now specified where the field recordings are kept.

Re 'Fair Flower of Northumberland': it might be better to find a tune that actually fits the words. Shoe-horning a song into an inappropriate melody (or the reverse) does it no favours, however anxious you may be to sing it. Be patient! Martin Carthy for one will tell you that it can take years for the 'right' melody to surface.