If I work through my own Personal Service Company on 'relevant' engagements will my client have to provide me with employment rights such as sick pay, holiday pay etc?

No. Under this legislation, the client will not become your employer. What the legislation does is to treat your Personal Service Company as making a payment to you chargeable to income tax as employment income and on which national insurance contributions are payable. All employer responsibilities fall on the Personal Service Company as they have always done.