Wool definitely creases, but with care it's pretty minimal. If you're sitting at a desk for most of the day, you'll end up with creases on your trousers behind your knees but these will mostly hang out over time.
Unless you go on to do a JD and work in law itself, it's unlikely you'd be required to wear a suit on a regular basis. I have a couple of friends who've followed that path, and only one of them is a daily suit wearer and that's in the corporate/financial law side of things. You might find better value in some good shirts (which you're getting) and a good pair of wool trousers (and perhaps a trip to the tailor to get them fitted) rather than a suit, particularly if you move towards the marketing side of things which is often a more creative endeavor and less reliant on corporate-style attire.
Put it this way. I wouldn't run out and buy a suit if you're just planning to use it for an interview in the short term, especially if there's a multi-stage interview process. A good pair of trousers will serve you well in many jobs for years, and you can always hunt down a blazer to match if you need to up the formality. It's not the suit, the wool S-number or the brand that will make you look professional, it's the fit and presentation and the way that you carry yourself. Have a chat to the folks making your shirts though, and ask them where they source their wool from. If they tell you and you can look up the company and check them out, there's a good chance you'll still get a bargain. I didn't mean to persuade you away from these guys, just to let you know that there might be some extra care and consideration required. After all, I'm only speaking from my experience and I've never seen the wool they use. Seeing as you've spent some coin with them already, I'm sure they'll be slightly easier to persuade to give you some more info.