Hi, I am going to be travelling to the US soon and I am looking to purchase a new mba. I would like the 8gb ram upgrade and the British keyboard options although this will require it to be specially configured. I would like to pick it up at the Apple store although I need to know the following: 1. How long is the maximum amount of time it will take to get my order to the apple store. 2. How long do they retain the item for after they receive it? Many thanks for your help!