Currently...

I am running, http://taskforceapp.com" rel="nofollow">Taskforce, a technology company based in San Francisco. We are in the productivity space, and have a focus on email.

My day-to-day involves all sorts of things: hiring engineers, dealing with customers, product design and some limited code, dealing with investors, and meeting potential partners.

Before I escaped...

Before moving to the West Coast, I worked for 'the man', in the City.

I left Cambridge and for about a year and a half my journey to work sucked, my job sucked, and I drank too much; it was time to make a change. 

My moment of truth...

I had started a business at university as well, but got lured into the offers of gold and quick riches by recruiters and friends at faceless corporations.

My realization was sudden. On the underground while sniffing someone's armpit for the second time that week, I decided I had to quit... straight away! I presented my resignation on the day, and was in San Francisco shortly after.

Planning for it...

From a practical perspective, make sure you are quitting because you have something lined up, or at least have a plan. I wanted to be an entrepreneur all my life, and have been in one form or another, so it made sense to finally take the plunge.

I think financing yourself is easier than people imagine. If you are working in the City, you must have some savings? If not, start saving, and have a few grand that will cover rent for 6 months, and then go for it, and find ways to reduce costs as well (share an apartment, go out less, eat at cheaper places, stop smoking).

Trying to get a business moving on the side is difficult, and takes far too long if you aren't full time, so I would recommend taking the plunge once you have an idea, or are pissed off with your current job.

The worst and best bits...

All I can say about breaking out on your own is the highs are REALLY high, and the lows are incredibly low.

There are too many examples of both to go into specifics, but if anyone wants to hear about mine, contact me.

Best advice...

'Build something people want', Paul Graham - I've got that on a t-shirt.

For anyone thinking about doing something similar, find a partner to work with if this is your first enterprise because having someone to talk things over with makes it a lot more manageable. If you don't want to, make sure you have like-minded friends to talk to about your decisions. 

I wish I'd known more about vesting periods and incentive stock options. 

Useful resources and information...

• http://news.ycombinator.com/" rel="nofollow">news.ycombinator.com - is an amazing community of entrepreneurially minded people where I found so many good links and resources; and it introduced me to a lot of really interesting thinking around building a business from scratch.
• Other more European/London focused resources: http://www.meetup.com/londonocc/" rel="nofollow">Open Coffee and http://www.seedcamp.com/" rel="nofollow">seedcamp.

Friends who had made the plunge before were extremely helpful, and have become quasi mentors. Approach people who have already taken the step - their advice/council will be far more encouraging than your friends who may be a little jealous of your decision. 
(full disclosure: I am a graduate of YCombinator, and a mentor for seedcamp.)