I'd like to join in, please, if I may? Have been reading the thread but only just got a moment to collect my thoughts and post.
I really need to have 31 NSDs this month as, due to the way my contracts are paid, I was a week 'light' at the end of Dec. Jan was always going to be tight but now it's really really tight and I can't even pay all the bills 
. So there will be a knock on for the next few months as I get straight again, though I've picked up a bit more work which will help. Plus I've some debts I need to try and clear - got arrangements in place but would be nice to try and clear some sooner.
Anyway, January is about survival. I am trying to manage on £100 per week to cover fuel, food, incidentals. It should be doable. But it would still be good not to use it all. This week I have been very lucky as my mum is still staying after Christmas and she insisted on buying some groceries - I didn't refuse 
. So the month so far:
1st- NSD
2nd -train fare to work (£4.80 but means a £5 saving on petrol + parking!) and had to tax the car - £75.00
today- work in car as needed there and had to buy petrol, milk and bread. But got petrol for next week (my week goes Fri - Fri) out of this week's allowance so am a little bit ahead 
So does it count for things like train fare to work? Or is it a NSD if I only pay for fare and nothing else, no coffees etc?
Weekend might be a bit expensive as have got to get DD1 back to uni and drop mum off on way, it's a 2 hour-ish trip, got the petrol but will likely need a coffee stop. But after that, it will be back to being me and DD2 - is a huge difference between housekeeping for 4 and housekeeping for 2, so might need even less each week - fingers crossed anyway!
Am going to aim for 12 NSDs - so far I think I have achieved 1!