Hello
You cannot add the weekends that you were not working to the 12 months. It is 12 months whether it is full time or part time as well. Please see this case, which discusses a person who works one hour a week for two years, and that this does not meet the rules for working holiday makers!
http://www.ait.gov.uk/Public/Upload/j20 ... ladesh.doc
[quote]12. While Mr Burrett argued that working part-time for the whole of a 24-month visit might amount to no more than 12 months at work, we cannot accept that this agrees with the purpose of the rule. First, in a working holiday which depended on being able to work part-time for the whole of one’s stay, one’s employment could not sensibly be described as “incidental to the holidayâ€