I'm going to be taking my first XC tomorrow. I told my instructor I was unsure about being able to find the target airport and he said "Honestly, it's no biggie if you don't find it...getting back here safely is all that matters".
Is this bad? Is this something illegal?
Not necessarily (for both questions).
If you don't find the airport and land there, the flight won't count as a cross country. So, you'll have to do it again.
But, as long as you don't enter any airspace you're not supposed to, not illegal. There's nothing that says you ABSOLUTELY HAVE TO land at that airport - You are the Pilot In Command now. If you can't find the airport, you may make the decision to return home. In a potential emergency situation, you may make the decision to divert to another field (FAR 91.3 is the most important one of all).
Or, as Pilot In Command you are also free to make the decision that you don't yet feel right about making the flight and want more instruction first. But if you feel you've had good instruction in lost procedures, then go make the flight!
If you follow along with your checkpoints and keep good situational awareness, you'll be able to at least find the general vicinity of the airport, and you should be able to find the airport as well. Airports don't move, so if you have built the correct picture in your mind of where the airport will be in relation to nearby landmarks (lakes, roads, and the city it serves for example) You should be able to look and see it right where it's supposed to be.
The closer you are aligned with a runway centerline when approaching the airport, the easier it'll be to see. If you're approaching perpendicular to the only runway and there's some tall trees on the close side of the airport, you may not see it until you're almost on top of it. So, if you don't spot it at first, maybe flying a few miles off to the side until you should be aligned with a runway might help you find it.
Also, I second the Google Earth suggestion. You can "fly" the trip before you go, and see what it should look like as you approach!