FNG got there before I did.
This is not at all a stupid question, considering the way nav is usually taught to PPLs. I too was taught that everything had to be 101% accurate. But it doesn't.
If you leave the airfield and set heading immediately, you'll be circuit distance from where you want to be, at the most. And since you can see the runway from the circuit, you can see your next turning point from where that'll take you to (useful to note it though, or you'll make a heading correction you don't need). Very simple really, once you know.
On a different but related point, your compass has markings at 5 degree intervals, so can you fly to the absolute accuracy you will have worked out on your whizwheel? This is expected in ground exams and for your instructor, but in reality it doesn't matter. If you're 5 degrees out, you'll be five miles off track 60 miles away (1 in 60 rule). So as long as you fly accurately and check ground features every ten miles or so, you'll never be more than a mile off track. And if you can't see that far you should be on the ground.
This is not an excuse for incomplete pre-flight planning or sloppy flying. It's just that from what I've seen there tend to be two types of PPLs: those who check everything to the nth degree, and those who've given up all that as being impractical, draw a line on the map and hope for the best, or use the GPS. So I think the PPL course needs a lot more in the way of understanding of what VFR nav is really about and what is actually needed in practice. Anyone else agree?
And for those who care, I still use my whizwheel. I actually rather like it.