In order to become familiar with the practice of herbalism in the UK and the educational training requirements therein, we would suggest becoming familiar with these organizations and the resources they provide so you can plan your education and apprenticeship accordingly:

It may be that additional training credits will be needed along with clinical training hours. Becoming familiar with the training requirements in the UK will be needed to understand this.

It is our understanding that apprenticeships are on the rise as more and more universities are dropping herbal medicine degrees (due to lack of government regulation).

You could potentially use the "find an herbalist" search feature on these websites to find local (or other) herbalists who may offer mentorships.

Keith Robertson runs the Scottish School of Herbal Medicine, which appears to offer apprenticeships. (Maureen Robertson, who is also associated with the school, wrote one of the lessons in the Advanced Course.) We are not familiar with Keith or his program, however, you may want to check it out.

Our understanding of the practice of herbalism in the UK is that as in the US, anyone can call themselves a herbalist in the UK (medical herbalists usually signifies NIMH, but there is no recourse against the use of the title without NIMH membership). Herbalism is not a recognized profession (ie. not statutorily regulated). NIMH tried for over a decade and the government finally said no. Herbalists are protected to practice under law as herbalists (thanks to Henry VIII), and anyone can call themselves one. However, that being said, it is best to become affiliated with one of the three organizations (NIMH is the most well-established and well-respected).