Being able to open your PDF documents in iBooks is definitely an important feature, and thank you for all that information you provided.
The first thing I would try is resetting your iPad using the following steps:
Press and hold the Sleep/Wake button and the Home button together for at least ten seconds, until the Apple logo appears.
You can find the full article here:
If you still do not have an option to save to iBooks after the reset, you might try backing up and restoring your iPhone (you can restore the backup after restoring the iOS software through iTunes). You can find the steps to do that in the following articles:
I hope this gets you back on track, Jacqueline!
Thank you for this. Resetting the iPad hasn't made any difference unfortunately. As I have quite a lot of important work stuff on the iPad that isn't purchased and stored through iTunes I am a bit nervous about ensuring I back everything up correctly. I will go to the local Apple store and see if they can help me to back up and then restore the software. I'll let you know how I get on.