If you just want fields with zero value not to display £0.00, all you need to do is to set up the "field format" accordingly.
Click on the range of cells where you want to do this,
Click Format - Cells - Number - Custom
Click in the box where it says "Type ... General"
Enter £ #,##0.00 ;£(#,##0.00);
That's pound space # comma # # 0 point 0 0 space semicolon pound bracket # comma # # 0 point 0 0 bracket semicolon space
£123.45 will display as £ 123.45 space
-£123.45 as £(123.45)
£0.00 as