Crossy is spot on.
For a credit card, the bank needs to see a regular weekly/monthly salary going into the bank.
My wife was a teacher and had no problems getting a credit card (to her delight).
Whilst I, as a director and no 'regular' salary, have a frozen limit in my account to cover my 'credit card'.
I keep a low limit to avoid fraud. When I need a large payment, I just put extra money on the card before I use it.
Not the best solution but it keeps my money safe.