I emailed DIC a few days ago and I just got this email back.
Thank you for your inquiry regarding Sonic the Hedgehog.
My name is Sherrie Ward-Guerrero and I work in the Home Video department at DIC. I am currently working on getting Sonic released on DVD in the UK and hope to have it available for purchase very soon. I'll do my best to keep you posted on the details when they become available.
Best regards,
Sherrie