I thought all accommodation was cheap in Swindon.
compared to London at least.
short term, long term, a week or two or a few months.
your period of stay and transport facilities would help people to help you.
some of the lads I know who do the Pylon work,
try find caravan sites and holiday chalets that are out of season and strike a deal.
i use premier inn/travelodge/ibis........... if you state you want the room for 2 weeks they will drop their daily price travel lodge knocked off 10 pound a day for me, went to ibis and they knocked 17 pound off because i wanted room for 3 months........ if you dont ask they wont tell you........ if you only using the room for kipping and showering they will drop their prices...... but pay it all at same time ..... you get a better deal...... im getting to old for sleeping in the van........good luck