The phone tariff that should exist, but doesn't

I'm coming to the end of an 18 month contract with O2, where I ended up spending £45 per month, to essentially have more minutes and texts than God at my disposal, when really, all I cared about was having a handset designed by people who understand that user experience is more important than features , and having a dataplan that let me use it.

Now O2 (I've been with them for more than 5 years, easy) haven't been terrible, but I've had calls drop on me, and where I work in Tower Bridge, reception is atrocious, but the market has changed since I bought a phone now, and I think there's a gap in the market that mobile operators are either ignoring, or don't want to publicise too much.

I don't need a new handset (and when I say 'need' I'm using the first world definition of 'need' here) - nothing out now is better than the iPhone 3G to the extent that the iPhone was better than the rest of market when I bought my first phone, and I can't see that changing anytime soon.

Now I'm going to outline a plan that I think should exist, but I can't see anything that fits this description:

1. I don't use the phone too much to actual phone conversations (no more than say 300 minutes tops probably)
2. I don't need visual voicemail or anything like this (Hullomail gives me everything I'd need now, and Google Voice as another alternative)
3. I do use my phone for watching videos, using twitter, and reading my choice of content online.
4. I'd like to use any data on my plan as a data I can use on when my laptop is tethered to it; I paid for it after all, right?
5. I'm okay with data not being 'unlimited' here, because I understand the how geeks are basically subsidised by lighter users anyway, but if I pay for a couple of gigs of data, _I want to be able to use it. _

Generally, paying more than £40 per month feels like subsidised phone territory here; for £5 more, O2 were throwing in a whole iPhone on a previous contract 18 months ago for example, so paying that much for just bits leaves a terrible taste in my mouth.

The closest thing I see are Vodafone's sim only tariffs, but they're not clear about tethering with iPhones (point 4 above).

I can't be alone here in being a iPhone user who isn't slavishly devoted to the newest shiny from Apple, but doesn't want to pay over the odds for using my phone in a different way to how most operators expect me to, and would prefer to use what they have in smarter ways, rather than buying more gadgets and dongles that'll end up in landfill in about 18 months time.

Is there anything else like this hypothetical tariff around? I really think there should be, and I'd it did, I'd join it in heartbeat.