I've been looking for the same thing.
So far I've found OneNote to be the best option, so long as you have it running on your desktop and are signed in on both your desktop and your ipad.
If you use OneNote on the ipad alone, it will let you write endlessly on a lined sheet of paper. If you mail it to yourself, it will produce a one page pdf. So not so good if you've written say 4 or 5 page - you end up with a narrow strip of very small writing as your pdf.
However if you run OneNote on your desktop, the two machines will sync so that as you write on the ipad it will pop up onscreen on your desktop. From the desktop OneNote you can save as a pdf over multiple pages. Or even export to Word and watch Word do a rudimentary handwriting recognition job (it really isn't worth it).
So far I've been doing this: noting in OneNote then saving and/or printing from my desktop.
A scanner would have been a lot less fun, but would have done the job.
