Not too far away from me then. Good luck on Saturday! I hope you've already found out lots about the car so it's not a wasted trip. Make sure you're all ready for the purchase, get an insurance quote etc as you'll need that before driving it back for four hours, and if you've got a quote already then its just a quick call to accept the quote rather than having to give all the details again. Oh and tax. Have the details ready so you can tax it too before you set off.
P.S. if you're going sat, make sure you know what time your insurance provider closes, you'd possibly be in trouble if you got there mid-afternoon, done then deal then called the insurer only to find they close at lunchtime on a Saturday.
Let us know how you get on.
Jamie