This link takes you to the Countrysideonline page for "Coronavirus and the Countryside" with information about use of footpaths and rights of way and various FAQs about being out and about at this time.
https://www.countrysideonline.co.uk/care-for-the-countryside/coronavirus-and-the-countryside/
A BBC article expressing farmers concerns for walkers in their farmyards and transmission risks
https://www.bbc.co.uk/news/uk-wales-52136726
DEFRA guidance on using footpaths and rights of way