Oh! First I have heard of T mobile uk getting the Bold!
This is what o2 said on their customer forum ~
Once again we've been testing various drops of software for some time now and it's still very unstable when used on a 3G / HSDPA network - it still suffers from call drops, network drops & device resets particularly when moving between cellsites so is in no fit state to be sold to customers. We don't have any software from RIM that's good enough yet but hope to get some soon and will launch as soon as we consider the firmware good enough. At the moment we hope to launch in September. I've been using a Bold for a while now though and it is a very nice device (when it works!) so you're well advised to wait for it.