To get a feel for rates and whats available try

http://www.uk.laterooms.com/sr.php3?...=0&d=0&n=1&b=1

This is late room availablity but it details what hotels/B&b's are available and the sort of rate you can expect.

Travel Inn and Travelodge are usually in out of the way (Motorway services) locations without the benefit of public transport, but in the case of Plymouth it does appear to be in the City.

Also "Please note that new retail units are being constructed next to the lodge, but disruption will be kept to a minimum. Apologies for the inconvenience."