Judging by the way you wrote about it, it sounds like you're most inclined to go to Warwick.
But let's increment through each Uni like a for loop.
Concerning ICL and people being crushed under pressure, if that sort of thing gets you worried like it does me, then don't get pressured to go there just because its claimed to be a "better university". The truth is that with that pressure it may be a worse University for you since it may induce stress and cause you to drop out and what not. So we can return a false for this one.
With UCL the facilities and place are great, I mean you're right in London. If cities are your thing and you have to be close to the busyness of the world then you should definately go here. If you like more of a peaceful existance or you feel that the city life may distract you more that your studies, then this is definately a place to miss.
I can image that the job prospects on UCL are not as great as ICL but are still up there amongst the top Universities since it is listed amongst the top 10 in the UK by the Guardian, Telegraph and Complete University Guide.
All computer science degrees cater for those without prior programming experience. If you were to go into a software development degree, things may be different but since a CS degree is designed for mathmaticians as well as developers then in most cases (probabably including UCL) there will be classes a range of classes for different people who have different amounts of coding experience.
Warwick is a lovely place with a lovely campus, as most people including yourself say. But in the way of a city life there is little to offer since the campus is in Coventry. However Birmingham is just a short 30 minute drive away and there are also trains that run from Coventry to Birmingham if you need anything exclusive to a big city.
Also, if you're conscientious about your finance then living in the midlands is MUCH cheaper than living in central London like with UCL and ICL. The further you go North-East from London, the cheaper it becomes to live seems to be the pattern.
Some people have also speculated that London is not a place to get a "University Experience". Since things are very compact and things like Campus communities are hard to forge because of this.
So the final statement goes like this:
if London is Esssential to your life
go to UCL
else
got to Warwick