This is a list of useful VAT guidance on Brexit published by industry bodies and leading organisations.
Solicitors
The Law Society: https://www.lawsociety.org.uk/support-services/advice/articles/no-deal-brexit-vat/
Accountants
ICAEW: https://www.icaew.com/technical/economy/brexit/uk-vat-implications-of-brexit
The EU
EC: https://ec.europa.eu/taxation_customs/uk_withdrawal_en
Consultants:
EY: https://www.ey.com/uk/en/issues/business-environment/ey-impact-of-brexit_on-indirect-tax
Accordance: https://www.accordancevat.com/vat-consulting/brexit-advice/