Welcome to the club!
Manu,
Your intent to have a prebuy exam is wise - especially as the airplane has what is called a "fresh annual." One of the sucker traps in aviation is for an owner who is trying to get rid of a junker to have it annualled by a mechanic who will sign it off although it is lousy shape. The owner then advertises it with a "fresh annual" and pilots who don't realize that the annual may have been nonsense pay more money than the airplane is worth and then pay much more money when they have their mechanic do a real annual.
As someone who fell into this trap 7 1/2 years ago, I can't stress enough how glad I am, and how important it is, that you're looking for an objective set of eyes to take a look at this plane. Even if you don't end up buying this particular plane, it can yield a lot of information that you can take into the next prospective purchase by knowing certain questions to ask ahead of scheduling another prebuy on another aircraft.
Lots of wiser ones than me have already shared the best advice, so I'll just wish you luck on the purchase and on the PPL journey.
Fly safely,
Brian