yet again you have got your wires crossed BTF, not for the first time
there is a difference in employment law between an agency worker and a contract worker. an agency worker is provided by and paid by an agency, the agency does have to offer them basic rights such as 28 days holidays, ssp etc
a contract worker on the other hand, who is contracted through their own limited company, does not have any of these rights.
the exception is if the contract worker has been with the same client, and on the same contract for 2 years, continuosly.
this is why most big companies will now only engage contract workers for up to 2 years, after that they usually have to go.
but if you are working on this basis, you have no entitlement to any sickness, holidays or any other rights