Conducting an International Job Search?
I migrated from the LA to London 2 1/2 years ago under the Highly Skilled Migrant Programme, which, if you qualify, is a very good way to enter the job market in the UK. You earn points based on your education level, number of years graduate (post university) working experience, salary, and other factors (bonus points for being young, an MD, or MBA from a top 50 school).
Once you get it, you can enter the UK without a job, look for a job for up to a year and switch employers at any time. Work permits are also possible but are much more restrictive since you need employer sponsorship, they need to "prove" that no one local could have done the job and to change employers requires a new work permit.
There are a number of good IT job sites in the uk (http://jobserve.com, http://monster.co.uk/ http://jobsite.co.uk/ http://progressive.co.uk/ etc...). I applied to many and got very few responses until I put down a friend's address and phone number in England. I was then able to get some telephone interviews, but didn't get a final job offer until after I moved over. Even though I was fortunate to get a job offer relatively quickly, I didn't start work for almost a month and a half, and didn't get paid for over 2 months (salaried payment in the UK is almost always monthly, often in arrears, which takes a bit to get used to). Contract work is also an option.
A very good website for the HSMP and UK immigration in general is http://www.immigrationboards.com/ a free discussion board, part of http://www.workpermit.com/ a worldwide immigration service (which I didn't use but might be an option for you).
Best of luck!