I did three months with Palletways and then went agency. I’ve had no issues finding work in the Midlands and until recently rotated between around three clients of the same agency so I was fairly settled once I knew each job.
I’m now working as a ‘long term agency driver’ (client’s words) and have worked every week day since November at 50p an hour more than most of the permanent drivers (however, this is balanced by me having to cover early shifts at short notice etc). There has recently been talk of them offering me a permanent job soon too.
So my experience hasn’t been bad with agencies, but I’ve encountered a few ■■■■ ones and found that generally have to haggle a bit (e.g. tried to tell me overtime rate was £15 but I’ve negotiated it to £18 after finding out others got that).