I had a similar experience when I was 18 (a few years ago now
) I was travelling along a national speed limit road and was approaching a bend. I slowed down accordingly and then spotted a big lump of debris (compacted mud) in the road, it wasnt really safe to slow down to much as I was on a bend and the road was wet so I tried to avoid it.
Unfortunatly there was no real way of avoiding it so I ended up hitting it with the o/s/f wheel. This flung the car into a spin, it hit the kerb which flung it into the air the car rolled a couple of times (on a grass verge) and finally stopped on its side after being brought to a halt by a sand stone wall (my head hit the wall, luckily I had light tints on the front that saved my face getting cut up to much - was still finding beads of glass in my head months after lol). Anyway I was knocked out and woke up with my girlfriend at the time screaming, hanging above me. I got her out and luckily a few people who witnessed what happened had stopped.
Police and ambulance turned up, we went to hospital. Police told me at the hospital that from all statments taken and their report that there was no way of avoiding the debris and I was in the clear (basically whoever came along that road first was going to crash). The car was a total write off but we got out alive and that was all that mattered, gf had to spend a night in hospital.
With the accident report from the police I went to the solicitors, he looked into the report but said I had to have someone witness the debris falling from a vehicle (which I didnt have even though the council had been doing some work on some land by the incident). I applied for legal aid but this was declined as there wasnt much chance if any off me winning. The car was insured tptf so I couldnt claim. So basically I think if you dont witness the debris coming off a vehicle or being left in the road there isnt much you can do.