You’re a shareholder in a company located outside the UK. As a perk you get to use the company owned flat, not only for business trips but also for the occasional holiday. Will you have to pay tax on this perk?
Unless you are a director, shadow director or employee of the foreign company (which has no presence in the UK, e.g. an office), non-cash benefits you receive from it aren’t liable to UK tax. However, you should check with the company’s accountant if you ned to pay tax in the other country.