Whether or not an employee is able to substantiate a claim for working from home, the employer can make a tax-free payment to cover reasonable additional household expenses incurred in carrying out duties of the employment under home-working arrangements.
There is a modest, but useful, increase in the tax-free payment from 2012/13 to £4 per week (we know, not the most impressive form of tax break around, but worth having!). To minimise the need to keep detailed records, this tax-free payment can be paid without the employee having to provide supporting evidence of the actual costs incurred. Larger payments than £4 per week can be made tax-free if supporting evidence is provided by the employer that the payment is wholly in respect of the additional household expenses incurred by the employee in carrying out his duties at home.
Controlling directors are not specifically debarred from this modest tax exemption, and there is scope to maximise the exemption if you are a director who regularly takes work home (are there any directors who don't do that?!).