When you're not really needed but employer seems happy to keep you on is their anything you can do?

[Clarebear81]

I seem to have been taken on just as a "Backup" when things get tough, 90% of the time I don't seem to have anything to do, I am floated around others to help them but you can just sense the resentment from them, they've got just enough to keep them ticking over and here I am stealing their work, needless to say, they don't talk to me and as I say you just can sense the hate.

When a big project comes in that's where I come into play, its all go go go get it done ASAP then leaving me nothing to do, I actually like the work when I have it but 90% of the time I am trying to look busy when I am doing nothing and its a hell of a long day 8-5pm doing this and when your coworkers don't really want you there.

Short of leaving (looking for another job at the min) is there anything I could do to change this?

As some PP have suggested, fine online education providers and start doing courses related to your area of work.
You can up your qualifications and be busy with something that might also, ultimately, be beneficial to both you and your employer.
I would be open with your manager about this down time, but definitely don't just sit there wasting your life - use the time to advantage.
Treat it as a positive time - you may never have this opportunity to study and improve your prospects again!