Posted: 05/06/2013 at 06:41
A bog garden could look gorgeous there and you'll really help the wildlife - you'll need to put a few more holes in the liner then you'll be fine - some helpful suggestions here http://apps.rhs.org.uk/advicesearch/Profile.aspx?pid=356 . Unless the area is naturally boggy (and it doesn't look it) you will need to keep the liner (albeit perforated).
If you could run a hose from guttering/downpipe on your shed and along the base of the fence, or to take overflow from any waterbut you have there, that'll help keep it nicely marshy.
Lovely garden by the way I really envy you that sunny wall!