Honestly if i was corbyn I would revive the old "Independent Labour" label.
‘Independent [Party Name]’ labels have been banned on ballots since the Registration of Political Parties Act 1998, which was introduced in response to a spate of candidates running under descriptions like ‘Literal Democrat’. I suppose Corbyn could register a party under a similar name, though again, the Electoral Commission could refuse it if they deem it plausible that it could mislead voters into thinking he’s the official Labour candidate.