Hello All,
Thanks again for your replies. I have made some adjustments and some progress! I can now put him down in his cot, even if for now it might be one sleep of the day, but he falls asleep in that sucking his dummy and me stroking his head. I have also stopped the "demand" feeding and am sticking to more of a 3 hourly feed schedule. Apparently my little one was topping up so much maybe he was getting too much of the fore milk and not enough of the hind milk, which is much higher in lactose and possibly upsetting his tummy (he had green poos so they said that was too much lactose). I have also dropped down my own lactose consumption (not that I had much anyway).

So here's hoping we've turned a corner!