Sorry to hear about your troubles!
There are a few options for you though.
1. You can e-mail your department administrator to see if he/she might send an e-mail out to the people in your course or other grad students saying that you're looking for a flatmate. Odds are, there's another person that's in a similar situation to you!
2. You can look on this website
http://www.spareroom.co.uk/ in your location.
3. You can also look on Gumtree, which is like the UK Craigslist. You're more likely to get scams and such with this one though, so be careful!
4. You can take the riskier option of booking yourself into a hostel for the first couple of weeks so that you can have the benefit of actually being there, seeing the places, talking to landlords, meeting potential flatmates, etc.
5. Your uni might also have some sort of resource for this sort of thing, so maybe get in touch with the International Student Office or Student Services and see what they say?
As for the landlord bit, it's hit or miss. They may ask you to pay a few months of rent up front, they may ask for a guarantor. It really depends. The one benefit is that if you're in a student area, they're going to be used to taking on tenants who have little to no credit (18-20 year old students for instance).
Hope some of this helps!