Help on pension when non-taxpayer

morg_monster

I work for a public sector organisation and earn about 25500 gross. I've been contributing to the work final salary pension since I started working there in sept 05 (aged 24, my first proper job). The defined contributions are 6.5%, or ~ £1600/yr, ~130/m for me
However, from October 08 I will be starting a full time PhD (funded by a 3 yr tax free stipend of £14500) and continue to work 6 hrs a week on the same (pro rata) salary. Earnings for this will be within taxfree allowance so I will be paying no income tax and no NI and will be suspending student loan contributions. So the only deductions from my pay will be work pension which will be about £250/yr (assuming they don’t have rules about minimum contributions). I will have ~£100 a month more monthly take home pay than now. I’m keen to make sure that I save the ~£130pm that would go into work pension and lock it away, but I’m not sure the best way to do this.
Other (possibly) pertinent info: I’m female. I will take up full time work again at the same place once I finish PhD, with a pay rise to reflect my new qualification, and will probably stay there at least another year if not longer. I’m looking to buy a house with my partner in the summer.
So far the options I’ve thought of are:

-Make AVCs while doing PhD (is there any point in this since I won’t be a tax payer?)
-Save ~£130 into high interest savings while I’m a non-taxpayer and then use it to make AVCs once I resume paying tax
-Start a personal pension for this period. I see that you get tax relief on up to 100% of your annual earnings now – for me this would be ~£4200 so I technically I can meet the minimum funding criteria of £3600 but I’m not sure I would be happy locking this much away at the moment. Also is it worth it for just 3 years although I guess I may find I want to continue to contribute once I finish PhD and my salary increases.

I have very little knowledge of pensions and knowing my work pension is a good one am just paying into it and thinking no more about it. So thanks very much for your help and suggestions!