The Health Protection (Coronavirus, Restrictions) (All Tiers) (England) Regulations 2020 has the following exemption allowing accommodation providers to accept a guest who is unable to return to their home. This would cover people whose homes have been flooded or have to evacuate in case of flooding.

Closure of holiday accommodation

14.(1)  Subject to sub-paragraph (2), a person responsible for carrying on a business consisting of the provision of holiday accommodation situated in the Tier 4 area, whether in a hotel, hostel, bed and breakfast accommodation, holiday apartment, home, cottage or bungalow, campsite, caravan park or boarding house, canal boat or any other vessel, must cease to carry on that business.

14.(2) A person referred to in sub-paragraph (1) may continue to carry on their business and keep any premises used in that business open

(a) to provide accommodation for any person who—

(i)  is unable to return to their main residence …

This would therefore permit holiday parks to accept guests who have to leave their homes due, for example, to Storm Christoph.