If you can't reach the PSN network you are doing it wrong.
To find your LAN Address:
PSVita Settings: Assign a Proxy to your Wi-fi connection on the Vita, set it to the LAN address of the computer running Fiddler.
with port number
Tools -> Fiddler Options -> Make sure it is set to port 8888 and tick the box called Allow Remote computers to connect.
paste this in the box for
Bypass Fiddler for links that start with:
Get your PSVita's, psp2-updatelist for your region.
since you have a UK Account here is the link:
Make sure you do these things:
Start the network logging program (Charles or Fiddler).
Do an internet test on the Vita.
You should get a website address that looks like fXX01.psp.update.playstation.net/XXXXXXXXXXXXXXXX'
click the drop down menu and click from file...change it's source to the psp2-updatelist file you downloaded earlier.
Inspectors Tab -> Then add a Query String named var
with the value 02050000It should work after that.