Quoting you all so you see this.
One option is to keep checking studentpad:
http://www.exeterstudentpad.co.uk/MessageBoardTowards the end of the term you'll see a lot of people posting up on there who are either first years who are one short for the house they want, or have already paid a deposit on, or second/third year groups who are staying in the same house but have one or two people leaving, so potentially you could find something there.
The other obvious option would be to go for off-campus student halls. There are multiple companies that operate halls of residence in Exeter, all of which are pretty newly built, pretty good value for money, and from what I've heard from current residents actually pretty good places to live. The main ones that I'm aware of are (company - blocks):
Spectrum Housing - Point Exe
Unite - Exeter Trust House, Northernhay House, Northfield
Collegiate Student Accommodation - Picturehouse Apartments
CRM - The Printworks
Lastly, as a second year I'm in pretty much the same situation as you lot. Last year I wasn't sure if I was going to be coming back for this year, so I didn't sort out a house till very late on and ended up living with a random group of 2nd and 3rd years, and will not be living with them again next year. I'm not going to be living with people I know from my course & societies because they're all either in settled groups or graduating this year, so I'm just waiting to see what comes along.
Sooo, let's make a TSR house!