I don't think such a law exists in England/Wales or in Scotland.
The Health Protection (Coronavirus) Regulations 2020 provide a wide ranging set of powers to the authorities including compulsory detention and/or keeping in isolation.
See
this link for the source of the information below:
"...Enforcement
13.—(1) Where a requirement is imposed on a person to be detained or kept in isolation under regulation 4, 5 or 8, a constable may do any of the following—
(a)take the person to a suitable place, specified by the Secretary of State or a public health officer, for the person’s detention or isolation;
(b)keep the person in detention or isolation.
(2) Where a person absconds from detention or isolation imposed under regulation 4, 5 or 8, a constable may take the person into custody and return the person to the place of detention or isolation, or take the person to another suitable place specified by a public health officer.
(3) A constable may use reasonable force, if necessary, in the exercise of a power under this regulation....".
Regulation 15 also makes failure to comply with restrictions or requirements, absconding or attempting to abscond from detention or isolation, obstructing a person carrying out a function under the Regulations, or providing false or misleading information to a person carrying out a function under the Regulations a criminal offence which can carry a fine of up to £1,000.