There's a database online under the name "demopals" but I've no idea if they're actually archiving the discs or just listing them. There are also some ISOs of demo discs available in various, but none of them seem to be from UK magazines as far as I can see.
Affiliate Disclaimer: Retromags may earn a commission on purchases made through our affiliate links on Retromags.com and social media channels. As an Amazon & Ebay Associate, Retromags earns from qualifying purchases. Thank you for your continued support!