Please help.

I've been making all sorts of the tartine recipes for a while now and everyone is loving them but having to make them in the dutch oven limits how many I can make in one go and I'm baking forever. I really want to follow the method that Dave Muller uses at Outerlands and use tins. His schedule is much more friendly and is clearly built around the fact that he has to sell lots of bread to make money from it.

I live in the UK so in general it is much cooler here. Overnight my kitchen drops to 17decC. I have been splitting a full tartine recipe into 4 and making 4x500g tins. However, there is no overnight rise and I'm baking bricks! I see in the tartine video that Dave's loaves rise overnight and he bakes them without anything to hold the steam in. Also he slashes them before the final rest and the cut seems to stay.... mine certainly doesn't.

So, who can help me?? I really need to nail this recipe to take the baking to the next level and be productive enough to start selling my bread.

Thanks

Chris