A question regarding Apple Macbooks.?

Hi there,
Next year I am going to University to study a BA in Photography. I am looking to buy a laptop, and I am set on getting Apple.
As I will be doing quite graphic editing, I need help on what MacBook I should choose.
I would really like the 15″ MacBook Pro. Is the standard 13″ MacBook suitable for what I need it for? Would I be spending an extra £300 or so just for bigger screens?
I would really like some advice, I’m hoping to buy it in December around Christmas and want to start planning on what I need.
Thanks,
