I'm wondering what you need the money for; how much and for how long 
All the good advise is never to borrow unless you absolutely have to and the problem when you have a poor credit history is that the good deals won't be available to you
FFS never borrow from a loan shark as they will end up breaking your legs or similar if you don't pay it back but not until they have truly bled you dry
You cannot build a good credit rating unless you borrow and pay it back, taken me 20 years to get that through to my eldest and his partner lol, they earn more in a month than others in 6 or 12, but spend it all and have no credit rating at all, just started changing that with my help, at last they are listening and I have him putting money to work, making more money, at the moment it is leaving them with little to spend so they want to get a credit rating.
The plan is working
Only ever borrow what you can afford to repay is good advice, not borrowing at all is not, and get in quick before interest rates rise too high, been renewing loans for years at very low rates and never been refused credit anywhere since.
Getting a loan and not spending it takes will power, but it is the quickest way to build your credit rating, along with using a credit card but putting the money by instead of cash or debit card and paying off monthly, if you can be disciplined it will pay when you need it.
If you never borrow and repay it can cause you all sorts of problems if that rainy day happens
The credit rating system is not foolproof either, calling them and getting it checked is no bad thing, they do fuck up at times. Sometimes it gets corrected the following month but not always.
Always try to get a soft search done if possible, and do not apply for different loans with different lenders at the same time, getting approved for them all can put a high risk on your credit rating search and mean being quoted higher rates or refusal, even if you have not accepted them., The offer still shows as available to you.
