It will totally depend on your flatmates. Obviously it is nice to be able to share, but some people may not have the same idea of sharing as you.
And I know some places get more than one fridge freezer, and you won't need to be putting too much in there, you're only eating for yourself.
Depends upon your flat, really. I think that most people in halls tend to have their own stuff though, and only when in private houses do people tend to share stuff.
You'll have to keep storage in mind when shopping, so that you don't buy more than you have room to store. Hopefully you'll have honest flatmates, so nobody will bother with notes in the fridge or whatever, but I would recommend using a marker or something on milk bottles (and other common items) so that you know which is your's - it can get confusing when there's about 5 bottles of milk in the fridge...
In my last flat of twelve people, we had three fridge freezers in the kitchen. That was enough for everyone to have one shelf in the fridge and one freezer shelf to themselves (everyone got to know who put there stuff where) and we each had two cupboards, one with a lock. Any spare space in the fridges was 'first come, first served', but there were never really any rows. Food did get nicked occasionally (it tended to be bread, fruit or cakes left out) but there were never any major problems. However, nobody really shared food and we didn't ever buy anything like bread, milk or pasta as a flat. Everyone bought their own stuff as stopped rows happening!
In my last flat (7 people) we all bought our own stuff, and had one shelf each in the fridge, and one in the freezer.
This year, I'm finding my new flatmates easier to get along with. We buy our own food but share things like bread, milk, mayo, butter, sauces; and we'd all be happy with people using our other stuff too because everyone's honest with each other and would buy things back; we still have our own shelf in the freezer but we share our fridge between us all - everyone leaves alone things that don't look like we should share them (i.e. yoghurts, alcohol) but share other things (milk, butter), which works well.
For me it was a case of over time you get to know people and start to go shopping together and say ok let's get this item between us. After time living with people you seem to develop little agreements that is ok to use each others mayo or butter. We ended up cooking together often too which meant food sharing, for example we would decide to make something and pool whatever we had or take it in turns to shop for a meal.
I bought all for myself because i dont like half of what my flatmates ate...
I spent about £20-£25 per week at tesco.