You will be surprised to be honest at how stubborn the market is; it is mature and they are not interested in new customers anymore.
o2 are the biggest UK mobile phone provider, they have 20million+ customers, they aim to keep their customers and increase IRPC rather than gaining new customers; they have a MASSIVE business department which accounts for a HUGE amount of of their revenue thank's to their former BT link and impressive buisness deals, there is very little for them to gain by getting a new customer, in fact they are more likely to lose money if they offer killer deals before they get a chance to see what you're usage is (it's the overusage they make profit on with residential customers).
o2 Unlimited Bolt On is good, but there are restriction's, as with any service. It can be used as per GPRS and 3G, but constant 3G usage will quickly eat up the Fair Usage allowance, and therefore for mass use of internet on the move, you will be better off with a mobile broadband solution like Totopop has.
If you are looking at the internet on the move, swerve the N95, in fact swerve it anyway, it's old hat now and battery life is shite (important if you are mobile). For internet to be used alongside a laptop, mobile broadband is the ideal solution, otherwise look for any 3G capable phone that can boast a good battery life, and that will suffice as you're modem.
If it is internet on a phone you require, do NOT get a phone, get a PDA-phone. Its a little fad they throw in with phones nowadays, and they do the job for the odd bit of browsing, but for any important use, they unreliable and tedious to use. So and XDA or similar is much much better, given the mobile QWERTY keyboards, touchscreen capabilities, Windows Mobile operating systems, interface and range of features and functions as standard.
If you really need a small package but that can suit most needs, the only realy option is the Sony P series, the latest (and greatest) of which being the P1i, it is the only
business class phone that boasts a QWERTY keyboard, great battery life, Symbian UIQ OS and the added bonus of a decent camera lol.
If you go for the business tariff's, you are much more likely to get a good and suitable business phone (such as a RIM Blackberry or an XDA) and you should get better deals on data, as well as the fact sales should try harder to offer you a good deal as they will expect you to be quite high volume.
o2 Buisness Tariffs: http://businessshop.o2.co.uk/