Posting this and hopefully helping others.
Yesssssss got 4G today on my trip to london..
not sure if its one of these three things below or a combination of two or all three as i did this steps in a non 4g place and couldn't test for a few days.
1. i flashed the UK Voda software, according to the LTE wiki vodaphone uk only uses the 800mhz band for LTE.
2. installed the app 'Advanced Singnal Status'
3. got a replacement simcard from the 3uk shop. (instant transfer of number to new sim no pac required)
in the 'Advanced Singnal Status' app, tap ADDITIONAL INFO, (on the other firmwares i tried it wouldnt let me in this section, says locked out or words to that effect)
in additional info, tap Device Information. and then i Set 'Preferred Network Type' to 'LTE/GSM auto (PRL)' then hit home to back out.
(NOTE: in the phones Settings > More Networks > Mobile Networks > Network Mode.. there still ISNT an LTE option, even when i was connected to 4G today.)
ive a feeling i would still have to use the toggle in Advanced Signal Status app after a reboot, as LTE still isn't showing up in the phones settings menu.
But ether way im happy. spent most of the day driving so didnt get to test out the 4G but google maps was streaming and my radio app was streaming
lovley, with a sexy 4G logo where i normally only see H+