If you’re happy with gravel/offroad, then there’s easy ways to link several classic routes together into a multi day epic. For instance, offroad from Wimbledon Common to the start of the Downslink, follow the Downslink to Shoreham, join the South Downs Way, follow that and end up in the New Forest, ride north crossing/along the chases till you meet the route of The Old Chalk Way, follow that to Norfolk. Reckon there’s at least 10 days riding there.
Other offroad options are the Badger Divide and Second City Divide, respectively Aberdeen to Glasgow and Glasgow to Manchester. That’s anything from 6 to 10 days of amazing riding.
Location: Milk & Beans