Yes they will do a check, because they won't lend out money not to get it back, regardless of the rates they are charging. They will make a decision on the level of debt, number of defaults seen and the likely hood of ever seeing their money again.
Wonga allocates 'trust ratings' to its customers. See here:
http://www.wonga.com/money/about-trust/
You'll obviously be given a low rating to start with (limiting the amount you can borrow) but, since the whole point of the service is to offer fast loans to people who'd have trouble borrowing from elsewhere, there will be very few formalities.
internet been off hour and half. thanks flump,I will get basic food and live on freezer stuff. Its next week i might be worse off as 2 urgent bills overdue
bagpuss , if you can manage without wonga you will benefit in the long run, can you talk to who ever you may be late paying ? Hang on in there , hope things improve for you x