Bit of risk, but if you can get a decent job from an agent before going overseas, that would rock.
I doubt that will happen. No one hires unless they at least interview you first. Any job that hires you without an interview is likely just a 'just get a body in that seat' type of job. Safety always comes at a price.
Contracting is much more developed in the UK than even Australia. Contracting is NOT considered a dead-end job: in fact many banks start people as contractors to see if they will fit in. Many of my colleagues started as contractors and then were hired as permies. They certainly don't think of contractors as second class citizens or anything, especially as the job market is good at the moment.
I started my first contract as a 3 month-er, and my boss kept extending my contract. I left temporarily after he said the work was finished, and then he called me back a month later saying he had a new project and money in the budget. I ended up working almost 18 months there, longer than some of the permies. I later found out that my boss had been capitalising my costs into the software project to avoid showing it as personnel expenses. I got a key to the office building (only my boss and the PA to the Managing Director had keys) and I charged the heck out of them (longest week: 63 hours). If you have valuable skills and/or do a good job, you can definitely develop your career in the UK.
I believe you can develop a career, make money AND travel in Europe even on a working holiday visa. What you can't do is develop a career and travel for 6 months a year. Drop your travel to the usual 4-5 weeks a year (UK annual leave is 5 weeks, by the way) and there's no reason why you can't develop a career as well.
Or you can try what I do. Work normally (4 weeks holidays a year) while overseas, THEN take a few months off between jobs.
Alex