I doubt they’ll have physical branches - the cost of doing so is so high. They’ll probably allow you to send in cheques via post and if you do need to pay in cash, then they’ll probably allow you to do so (in time) via the Post Office network (as many banks do anyway).
Personally, I can’t remember the last time I needed to pay in physical cash to my bank (I’ve had 3 cheques in recent memory I’ve had to pay all: all from HMRC! - apart from those, I’ve not had any cheques I can remember!). I think it’ll be a bit of a waste of resources and cash to run any sort of branch network (including the post office one).
The only times I’ve been into a branch in recent time is to pay in 2 of those 3 cheques (as I was nearby anyway - the third is going by post) and to close a business bank account with HSBC (we moved the business bank account to Cater Allen who don’t have any branches)