Simply contact the lenders and explain the situation. If their actions follow the normal pattern, the credit card companies will suspend the interest on your account and agree to accept small payments each month until your financial position improves. (You'll have to cut up your cards and send them back to the credit card companies). Don't let them persuade you to offer more than you can afford. Some firms will accept, say, a tenner a month without the intervention of any external body. Other firms won't accept less than 1% of the outstanding balance unless you arrange a payment plan through an recognised organisation such as the Citizens' Advice Bureau.
The bank might be a little more difficult to deal with if you've got a current account with the same firm. They might try to draw upon the funds in that account to reduce the loan. It could be a good idea to open a 'basic' account, with another bank, to have your JSA paid into. Even so, most banks are reasonably helpful.
Don't get too worried about your debts. Lenders will nearly always accept minimal payments when you've got a very limited income. If they don't, all they can do (in the first instance) is to take you to court to obtain a County Court Judgement against you. Since that would only order you to pay what you could afford each month, they don't really gain anything by following that route.
The really serious problems which can arise from being in debt (like having bailiffs turn up to seize your belongings) can only occur if a lender has first obtained a CCJ and then you've failed to keep up with the payments.
For further information and advice, contact CCCS. (It's an independent charity dedicated to helping people with debt problems):
http://www.cccs.co.uk/
Chris