Credit Report clean up - what next?

I'm trying to clean up my credit report after I discovered I had incorrect information.
For years I've had problems with my credit but I thought they were due to too much total debt and a couple of missed payment (most recent July 2011 and never more than one payment). The missed payments were partially absent mindedness and my own stupid fault when moving jobs.
I have had incorrect data removed from Equifax (Santander didn't close an account, account fees acrued and then they settled the debt. They've agreed I'm right and have removed it)

So what next? Do I have to do the same with Experian and/or anyone else? Also should I be closing catalogue accounts (which I do use occasionally as I can't get a 0% credit card at the moment)? and should I do anything about my settled accounts? I'm a bit of a newbie on these things I'm afraid and I'm now putting effort into becoming debt free within 4 years to try and look to buy a house before I'm 35. I have 4 years left on my late payments but as they're only 1 payment on 3 occasions I don't think these will have a drastic effect.

Current outstanding debt:- £7650
Current total limits:- £10,800