Mobile internet?

I am in the UK looking for advice on getting mobile Internet,





I believe I have three choices, but which one would be best?





Smart phone


PDA


BlackBerry





My main issue is that I am short sighted therefore I am looking for the largest screen possible. I will only need the internet access for about 6 weeks of the year (holidays)





does anyone use any of these companies and can recommend a good deal,





Vodaphone


Orange


T-Mobile (no connection when I was in Lanzarote -so not suitable)





I see that Vodaphone offers a modem stick, but I do not want to take a laptop as it would not fit in the room safe, so maybe a PDA would be better with this option? or maybe I should get a PDA with built in modem? or Blackberry?





My main internet access would be to browse my support system a demo of which can be found here; http://demo.whmcs.com/mobile/





Username: Admin


Password: demo