I know from living with someone who studied creative writing that although there is no specific society (that I know of) the students often socialise together. You may also find opportunities to do extracurricular activities in conjunction with the Theatre, Film and TV department as a script writer if you so desire!
If it's a community spirit you want Aberystwyth has that in abundance! the small town creates that for you, You'll also be able to find societies catering for pretty much every taste from caving, chess, rock music to glee.
Most departments have a society of sorts, if it so happens yours don't, make one. New societies are always popping up, from the departmental ones to the weird and wacky ones... (Zombie apocalypse society being one of my favourites recently)
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