I was actually looking for a place this past two weeks. Glad to say I found one without the use of an agency even though I did sign up with a few and was showed a few places.
They're NOT interested in helping you find the right place nor do they listen much to your requirements. Example, I gave a budget of a £1000 a month for a one bed at a 6 month let. I'm moving back to my current house in the new year as renovations will be completed then, so I wasn't looking for anything fancy. Thousand bucks would've been enough.
First place I was showed the rent was £1500 a month.
Second place (after having a go at the idiocy of the first showing) was £1100 and a year's let without a break clause. At this point I walked out of the place and told the kid that was showing me the place to **** off.
The owner of the agency rung me the next day to apologise and offered to personally show me a place that was £950 a month. I checked on their website and it was actually up there for £875 a month. Agency got told where to go.
Found another agency that specialises in cheaper rent places. (yes, dumps mostly) Got showed a few places at rent varying from 850 - 1000, places where I truly and literally would not keep my pet cockroach in.
They were only interest in shifting their 'fish places', you know, the type that's been sitting on the books for a while and was starting to reek.
In the end I got a stunning place in Hampstead for a 1000 bucks a month all inclusive through a friend of a friend. Agencies in the future? I'd rather cut my own testicles off.