Hi monkeyboys, welcome to this section of mumsnet... not seen you around before
I'm a nanny and I work in Surrey (just about), actually right on the Surrey/Berkshire border. Sounds like you may be in a similar area, if so do feel free to contact me directly, if your nanny would like to meet another local nanny (I care for children aged 9mths, 3yrs, 4yrs and 9yrs - older two at school most of the time).
In my contract, I have all meals whilst on duty. I work 7.45am to 5.45pm, so my employer provides lunch and tea - both of which are eaten with the children, and which are typically the same as the children. My employer does not get any food especially for me... I just use whatever is available in the home, which I will occasionally supplement with things from the local farm shop (for example, got to work this morning to find that only veg left were two leaks and some potatoes... so will get a few carrots and other veg from the farm shop to tide us over until the veg box delivery).
Outings, we go to Legoland (it's open in a few weeks ), Lookout, Coral Reef, Windsor Great Park and various other places. Legoland usually involves taking a packed lunch, though sometimes we will splash out and get children's fish fingers meal deal (as a annual pass holder, we get some discount on meals). This comes out of my weekly kitty (£20), so it can be a large amount of the weekly kitty. I always go to Legoland with a friend (much easier having 2 adults and a group of children), so we take it in turn to buy adult things like Coffee - this I use my own money for. Legoland passes I pay for myself... would be nice if my employer would buy those, but it's a big expense, and I don't have to go to Legoland.
So as others have said, allocate a weekly kitty for activities/eating out, and let your nanny decide what to spend it on. Once it's spent, no more money till beginning of the next week... your nanny will soon learn to budget for things, plus finding cheap or even free activities to do!
I met an agency owner recently, who said that she sent just one nanny for interview with a parent, and the nanny got the job. I wonder if you are the parent concerned... could be, if you are local.