Yes, part-time work is eligible, but you have to prorate it - e.g. calculate the full-time equivalent. And of course it will take a little longer than a year (52 weeks) to qualify. For example, if you work 25 hours per week every week, it will take 63 weeks to qualify (1560/25=62.4 weeks, round down).
You can calculate it as per monkeyspanner's description. Or you can simply add all hours and divide by 30 to get the # of FTE weeks, but you can only use a maximum of 30 hours per week (example, if you worked 35 hours in one week, you can only count 30 hours).