Tao, because of the ease at which a plotted route can be modified, I think I would suggest Microsoft software even in USA/Canada. But that's just a one person opinion, nothing more and nothing less. People do use other software successfully.
Other software in the UK to explore would be a product made righ in the UK, by Directions LTD:
PC Navigator 9. There is a truck version available, too, (and they plan to release a truck version for USA/Canada, too).
Still, even if a product advertises the ability to route large trucks, do not rely on it. Especially a new driver should not rely on it.