You're right on that bit. The section of legislation is here:
Right to be accompanied
14. - (1) This regulation applies where -
(a) a meeting is held under regulation 3(1) or 8(1), and
(b) the employee reasonably requests to be accompanied at the meeting.
(2) Where this regulation applies the employer must permit the employee to be accompanied at the meeting by a single companion who -
(a) is chosen by the employee and is within paragraph (3),
(b) is to be permitted to address the meeting (but not to answer questions on behalf of the employee), and
(c) is to be permitted to confer with the employee during the meeting.
(3) A person comes within this paragraph if he is a worker employed by the same employer as the employee.
(4) If -
(a) an employee has a right under this regulation to be accompanied at a meeting,
(b) his chosen companion will not be available at the time proposed for the meeting by the employer, and
(c) the employee proposes an alternative time which satisfies paragraph (5),
the employer must postpone the meeting to the time proposed by the employee.
(5) An alternative time must -
(a) be convenient for employer, employee and companion, and
(b) fall before the end of the period of seven days beginning with the first day after the day proposed by the employer.
(6) An employer shall permit a worker to take time off during working hours for the purpose of accompanying an employee in accordance with a request under paragraph (1)(b).
(7) Sections 168(3) and (4), 169 and 171 to 173 of the Trade Union and Labour Relations (Consolidation) Act 1992[4] (time off for carrying out trade union duties) shall apply in relation to paragraph (6) above as they apply in relation to section 168(1) of that Act.