AGENCY WORKER FURLOUGH / SICK PAY ELIGIBILITY

I’m an agency worker and my last assignment ended 31/3/20. As this was a pre-arranged date, I’ve been told I’m not eligible for furlough as my assignment did not end specifically due to coronavirus. However, I’ve been unable to work since as I’m having to shield. Firstly is what the agency say correct and if so, would I still be considered an Agency employee for the purposes of claiming sick pay or do I no longer have employee status now that the assignment has ended? Thanks.