Sadly, tickets for the music/variety night 'Iain & James Set The Agenda' (where Cellarscape are playing a mini-set) at The Camden Head has already sold out in less than a day. You can try for returns on the day at the venue: http://www.camdenhead.com/ but this does not guarantee you'll be able to get in.
Next chance to see Cellarscape live will be on Record Store Day (Sat April 16) inside Head music store in Bromley:
http://www.facebook.com/event.php?eid=118415551566584
Further live dates are coming for the rest of the year too.