What people say about black boxes isn't really true. They aren't limiting, as long as you don't drive like a total tool. The roads are so busy now that you rarely have the chance to speed anyway.
I have a Polo 63 plate match edition and while it's only a 1.2, it's perfectly capable of sitting at 80 on the motorway. The only thing I wish was better was the economy: I get about 44mpg on a long motorway trip. I would also add that as you have never driven before, how fast the car is really isn't an issue as you aren't used to anything else.
Go second hand. You'll almost inevitably do some damage, whether that be kerb the alloy, or touch the bumper on it etc. You'll be way less sad if its a few years old. The car will have also done more of the depreciating by then. It also saves more money for insurance, petrol, tax etc. These all add up.