I just got a little further on this.
Not sure if this will help you or not, but if you take out all the #'s - it correctly does not display a 0 value - the problem at this point is that you can't have comma's separating the thousands
so for example:-
\# "£,0.00;-£,0.00;''"
a value of 0 is correctly not displayed at all
a value of 1234 is displayed as £1234.00
and \# "£#,##0.00;-£#,##0.00;''"
a value of 0 is incorrectly displayed as £0.00
a value of 1234 is displayed as £1,234.00