Thanks to the omnipotent Bill Gates, the most popular DTP software in the world, as well as the UK , for home use is probably Microsoft Publisher.
The various Serif packages are in second place due to their good value.
As far as professional use goes, my own favourite is Adobe Illustrator although Quark is probably used by just as many professional designers - I cut my teeth on Quark Express 4.0 at college.
Most of the newspapers in the UK are set out using one or the other of these programs.