OK thank you purple 
I guess if I can get him in the habit of naps at more regular times it might become easier to get him down for a nap without having to spend ages rocking/bouncing/pushing the pushchair! It's worth a shot!
We don't even have a set bedtime atm, I was starting to establish it and then went on holiday which messed things up. Last night he went to sleep for the night a lot earlier than usual which took us by surprise. He must have been tired.
Definitely feel as if I'm guessing most of the time!