credit ratings and getting a job

I had a interview for a job last night and next week, they want me to go in for an 'assessment day' to see whether or not I am suitable for the job.

Now, I really want this job but to get it, you need a good credit history as its an insurance company.

Recently, I applied for several personal loans but got declined. How much of an impact will have this had on my credit rating as I know it isn't great. I also applied to extend my credit card limits but was declined for those also. I have had my credit cards for about errrr a year and a half now?

When I got my first credit card, I think I missed one or two (I think its one...) payments as I didn't open my post in time and thought my payments would come out of my account automatically. I was very silly. How much of an impact would this have had? This was over a year ago now. How long does it take to wipe this off your file?

I have about £4000 on credit cards and have 3 payments each month as I have 3 credit cards. I am paying more than the minimum amount, alot more at the moment.

Do you think I'll be ok and pass it? Also, as I'm not applying for a loan or anything, how much information can they actually search on me? Will they just see my overall credit score or my whole file?

I've been told I only need to worry if I've missed 3 or 4 payments and have CCJs and stuff (which I don't) but I'm just worried as I've been declined for things lately.

I just don't want it getting in the way of me getting a new job as I really need to get out of the place I am at the moment as they are making us all redundant soon anyway.