I dropped it to a mechanic I trust who knows peugeots quite well, and he discovered the fans weren't kicking in, and ended up replacing my radiator, one of the fans and a relay, but did mention that the fans were still intermittent for some reason, but they were kicking in at high speed. I needed the car urgently so took it off him as it was.
Now the car still doesn't overheat, it sits at about 80 degrees on motorways and open roads, but once in traffic it will climb to just under 110 degrees before dropping back to 90 again, and sometimes it won't go much above 100 degrees.
Pulling the brown sensor on the thermostat housing makes the fans come on, but pressing the A/C button doesn't.
Where do I go from here?
Colm