Most of these "loss of earnings" type policies pay out so little in relation to what you pay in that its not really worth it. Also, they have lots of exclusions and get out clauses. Falling off a ladder would almost certainly be not covered.
If you have the self dicipline to do it you can "self insure". Open a seperate high interest building society account and pay in £20 a week by standing order. Don't use the account for anything else.
After a year you will have £1000 in there, this is about the max you would realistically hope to get paid out from one of these insurance schemes in the event of a bad accident (tops).
Don't stop there, keep paying in and it will grow into a nice little nest egg in a few years. The good thing is its still your money. If you paid it into an insurance scheme it would be gone.