Hi there Jason,
Welcome to the forum :thumbs:
Swindon hey, well yer quite spoilt for choice really as you've got the Bristol Avon virtually on yer door step,
There's about 1.5 miles or so of free fishing on the Avon at Chippenham and has most coarse species but is really renowned as a big roach venue but location is key here, I know the river there quite well as I used to travel from Kent to fish there quite regularly a few years back,
I'd surgest that yer best bet is to call into premier angling in Chippenham and speak to the staff about any further updates,
Don't forget though that there's only another couple of weeks left on the rivers until 14 th March when the season closes, it'll open back up again on 16 th June,
There's a variety clubs on the Bristol Avon aswell around areas like Melksham etc,
There river Kennet and upper reaches of the Thames above Oxford may well be worth looking into aswell.
As for stillwaters I can't be of much help to you unfortunately because I hardly fish Stillwaters nowadays as I just purely specialise in rivers and then rove about on old overgrown canals during the close season
Be lucky