The times when construction jobs were often frowned upon are over. Working in construction, even if you start from the very bottom positions, is something that is gratifying and has good progression prospects. It's the kind of jobs that's often hiring, and a variety of skills are learned from working the job and learning from the more experienced co-workers. Be it for repairs or construction of new buildings, there's always something that needs to be done, especially in a large towns and cities.
Demand for construction workers is going to be increasing in the next few years, as London and, to an extent, the whole of the UK prepares for the 2012 Olympic Games. That means that construction jobs will be in high demand, and will probably pay well, because the deadlines will be tight. This means that people looking for their first job in construction will have a chance of showing what they are made of and show people that they are serious about it. It'll also be a great learning opportunity, even for people who already are seasoned construction workers, as the architecture for the Olympic Games is said to be spectacular. You have a chance to make your mark and be a part of this great event.