It can be done by oneself, but it does take a few years of repeat spraying. (We had it in our last garden, before we moved to this area). The remains burn well once dead and quite dry.
These days there is a new way to tackle it, and that is via an injector gun. They cost circa £250, and have to be used when the plant is growing strongly. The weed killer then gets directly into the core of the plant, and it apparently means it is quicker to eradicate.
Ideal if you develop a personal vendetta against the stuff, like I did.