I seemed to have fixed my issue!
Somehow my access point settings were wrong. I had my Proxy as "", my Port as ) and my APN as general.t-mobile.uk
I used the following settings and it's working. Not sure how this got changed!
Name: T-Mobile Internet
APN: general .t-mobile .co .uk
Proxy: <not set>
Port: <not set>
password: ** (sorry, don't know what it is?)
Server: <not set>
MMSC: http :// mmsc. t-mobile .co .uk: 8002/
MMS Proxy: 188.8.131.52
MMS Port: 8080
MMS Protocol: WAP 2.0
APN Type: * (sorry, don't know what it is?)