The HDD in my MBP began behaving oddly. It made more noise that it should have made and I guess I realized that I might have a major issue when I couldn't copy some files onto my backup drive.
After attempting to backup some very important files and receiving error message after error message I opened Disk Utility and ran the verify and repair disk permissions. The result weren't good and knew something needed to be done immediately.
The Waiting Game.
I ordered a new hard drive (I decided whilst I'm at it I may as well get more space so I upgraded from 500GB to 750GB) and then just had to wait patiently until it arrived.
In the mean time, I managed to back up everything I needed by finding the files that were in the faulty sections of the drive and replacing them from previous backups (phew, I think I was incredibly lucky there).
Once the new drive arrived it was so simple to install. The hardest part of this whole process was just waiting for the new drive to arrive. I had to continue using it as I had work on there that needed to be finished and no other options.
I think I was really fortunate not to loose everything and I have learnt that I should back up as often as I can. The more backups the better