Give the BHPA a call, they will direct you to your nearest examiner, he will want to see you fly and check out your flying skills, he will then apply for your papers, they cover four areas, 100 questions, 25 on each subject , you can find the study material here: http://www.jfdiuk.com/pilotNotes/pilotNotes.html
on joining the BHPA you are covered by their insurance, but only when flying in the presence of an instructor until you get the rating.
you can find contact details here,
http://www.bhpa.co.uk/
Tell them you are already flying a paramotor and want to take the alternate entry route and they will sort you out.
good luck.
Dave