Chris Green wrote:

If you're as old as me you may be able to go on a 'Grandfather
Rights' training course and become licensed/legal to spray effective
weedkiller yourself. This is what I did and so I can now continue to
spray herbicide on our fields (to keep the ragwort down) and on our
drive to kill everything.

Your grandfather rights exemption expired 3+ years ago ...

http://www.hse.gov.uk/pesticides/topics/using-pesticides/codes-of-practice/guidance-sustainable-use-ppp-regs-2012.htm