I'm thinking of the June course run by one of the guys on the forum called IanDarkPeak - his course looks great. You can find him around the forum a good bit of the time, or else his website is
http://everythingoutdoors.co.uk/
EDIT: Of course, there are other companies and individuals who offer nav training courses, including the FRA themselves. I'm not in any way endorsing one course over another - they all look great, it's just personally Ian contacted me when I mentioned wanting to go on a course when I joined the forum.