The way I found a darkroom was with Ilford's great search facility. Go to their B&W photo site, Ilfordphoto.com, hit 'photo community' --> 'Darkrooms', type in your postcode and a radius (I'd suggest 50 miles, you are in Yorkshire after all :P).
http://www.valeofyorkdarkrooms.co.uk/ This lot are fairly close to Barnsley.