We have an AP (on our third).
We live in rural SE and pay £60 pocket money per week for 25 hours + one night babysitting. We also pay for her college course (£125 per term), her YP railcard (think it was £30), provide a PAYG mobile with £10 credit at the start, phonecalls, computer with Skype, full board for meals and approx £60-80 per month on joining us for days out/coffees out/meals out. We don't give them use of a car because we live near a station. She has her own single room but shares family bathroom. In her room she has tv, dvd & hi-fi but she always watches TV with us.
I have one 2.8 yr DS. Her time is broken down as follows:
Mon : 9-5: Hoover downstairs, mop, meal prep, laundry, ironing, then available for DS
Tue: 9-11: Change DS bedding, laundry, get his swim stuff ready, take him swimming. 3-5: meal preps, then play with DS
Wed: 12.30-5: Clean bathroom, meal preps, laundry, then available for DS
Thur: 9-11: Empty upstairs bins, laundry, ironing, be available for DS. 3-6: DS and also fully cooks evening meal for all of us
Fri: 9-5: Hoover whole whole, laundry, then available for DS most of the day.
Her weekends are fully off but she is welcome to join us in most aspects of ours if she wishes (however, once they have beenw ith you a while like ours they tend to have their own friends to see, at the beginning it is more labour intensive). Every day tasks also include emptying and loading the dishwasher, wiping the dining room table and DS' toddler table, and maintaining tidyness of the toybox.
And they aren't necessarily the cheap option - our current one just has to look at something at it breaks/gets stolen. And feeding her isn't cheap (not that I begrudge that in any way but it would be wrong to think they are cheap, it's just that the vast majority of their costs are hidden). And of course there are birthdays/easter/xmas which you should want to make special as they are away from home (AP's bday probably just cost me about £150 including present, meal out, day out, cake, etc etc). So please do not just go with an AP because you think they are cheap. They are also much more a part of the family than any other form of childcare - they are meant to share your family life and home and you must be prepared to have someone sharing your lounge, helping themselves to your food etc.