Yes and No Nigel,
registering your 'Garage' entirely optional, although they ran a competition to win a Hypermotard last year where you got one lucky dip entry per bike owned.
you do need to check whether you're affiliated to a club in the 'Desmo Owners Club' section (1)
If you are, any clubs show at the bottom (2), if you aren't you can 'Join A DOC' (3)