Just out of unrelated curiosity, what has winter been like that side, this year? I ask, because ours has been wildly warm. July to September are usually our coldest months and we have had temps as high as 31 degrees.
I think you will do well with the Potch birds. Hard to beat something that is bred locally, for local conditions. If you get birds bred in the middle of the UK, it is like getting a husky for a pet, when a Boerboel would make more sense.