I've been through the PPI process twice now myself, on both occasions, through two seperate PPI companies, the check/settlement is originally sent to the PPI company, they then issue you a check from themselves, with their share removed (anywhere from 10-40% or more)
The lowest cut I found was around 30%, but supposedly there are other companies which offer lower rates
It's a good idea to shop around.
Let me know if you have any further questions.
Also, be sure to read this page, before claiming - http://www.fscs.org.uk/your-claim/claim-management-companies/