Hi Neil,
I'd love to give you advice, but, being from the US, I'm at a loss as to what you're numbers actually mean.
For instance, what is a backlog? Whether or not this sort of thing will be on your transcript, I do not know. However, your university will know. Ask the registrar's office, or get a copy of your transcript for yourself and look at it. If you feel like you need to justify your poor performance in undergraduate, do so in your personal statement. This won't take away all of the problems, but if you provide a decent argument for yourself, then you can have a fighting chance.
I wish I could give you more advice, but I am at a loss as to converting your profile into units that I can understand.