A great introduction to the botanical key, the main one used on the course is: The vegetative Key to British Flora by John Poland and Eric Clements. The course is designed for those who have never used a botanical key and no prior knowledge is required.
I can only go by the conditions at Bushy park on 23rd June 2018 where the sun was shining, and we spent a great deal of time outside. The session started off with the tutor Rachael in the classroom explaining about the botanical key, how they work and also explaining some of the jargon. There is a lot of jargon and abbreviations to get and your head around.
We then moved outside in a managed grassland and worked in small groups with the key to identify different wild plants in the area. After lunch we wet to a different area of Bushy park with a slightly broader range of flora.
I would highly recommend the course especially to those who want to work in the field but have limited field identification skills. This course is an excellent starting point for the beginner.