AT&T / HTC OTA updates overseas?

[s1mon87]

I'm in the UK and I refuse to buy the HTC A9 in the 16GB / 2GB RAM version that's available in this country due to it being more expensive than actually importing one from overseas with twice the memory and an extra 1GB RAM. That said, I've been struggling to come across a brand new and sealed "unlocked" phone on eBay apart from these dodgy HK sellers with heaps of negative feedback. The only one I've come across is an AT&T variant from the US. I was wondering if I would receive the OTA updates with this being a carrier branded device and also, if I did unlock it, would that AT&T text stay on the top bar of the screen where the notifications show or would it change to the name of my carrier when the SIM is inserted?

Thank you.