Pretty sure UWE has Wifi. Whether the organisers need to get the code or not is another matter but I do know I had to go outside during the model train thing to call my lift as couldn't get it inside....
There will be wifi you'll need to sign up for it (I'm no techie, as many of you do know!) so I know very little about it. Plus it depends on signal and your own providers (I'm with a well known phone company whose coverage can be variable *nod*). But it will be free. Yay for free!
If you're able to, it might also be an idea to build up a little data allowance on your phone as well. Won't be much use for video, but you can still follow social media, check weather forecasts, message friends etc. No idea what phone coverage is like in there -- I know it's pretty variable in big buildings -- but it's a useful backup when Wi-Fi isn't doing its thing.
The WiFi is public and free but does require proper registration. We tested it twice, including during a visit when a event was on, and got good reception.
Mobile phone reception was also checked during the visits with good signal and speeds during an event, but probably not as data hungry as we would be. So, you're probably fine on both counts but would be a good idea like Logan suggested to save up some mobile allowance. We cannot guarantee the reliability of the the WiFi or mobile as it's out of our hands.