As reported on a Sow Seeds e mail I received just now
Michael Gove MP, UK Minister for the Cabinet Office, stated this morning on the television that going to and tending your allotment was considered exercise and therefore allowable under the more stringent rules for slowing the spread of the coronavirus
Please continue to keep at least 2 metres away from other people – more is better! Remember the virus can be spread by contact from surfaces so if you touch something like a gate, padlock or tool touched by someone else, wash your hands with soap and water (even if cold) or use a proper hand sanitiser”
I hope this helps to clarify the situation a little
Keep well
Dave