Writing a Part Time Support Contract Suggestions

[TechSupp]

I am looking to change my role ( and more importantly how much of the week I work!) in September and I am going to be dropping my full time role covering a few schools for tech support and just looking after one primary school on a part time basis. Its to be on a fixed hours per week but on a flexible timescale i.e. no fixed start and finish times or days. Talked to the head and hes happy with that but we need to put something down on paper and I'm not sure where to start. Anyone else have a similar agreement they would like to share or have any suggestions what to put down. I cover virtually any eventuallities with the curriculum network or arrange to sub it out if its beyond by caparbilities or its more cost/time effective. Probably looking at 3hrs a week and thought if hours were accumulated they could be used in holiday time for installs or even at an agreed rate to do some project work with some of the kids (I'm a qualified teacher, hangs head in shame on here , but at least its now allowing me to work part time! ) I'll still be lurking around on here as I will still be doing tech support for two other schools I teach at but that is an agreed part of my role there.