Your companys expenses can be paid in two ways, directly from the company account or as a reimbursed expense when paid for out of your own pocket.
With regards to reimbursed expenses, directors are able to refund themselves at any time from the company account, but must keep receipts to justify the expenditure. The rule of thumb when claiming for expenses is that you can only claim within HMRCs parameters, which define allowable expenses as being wholly and exclusively incurred in the performance of your duties.
HMRC will allow your claim if you meet these conditions. When theres a dual purpose to your claim its unlikely to be accepted, because the expense would be needed regardless of the business, for instance, clothes. However, if the dual purpose is only incidental because of a business necessity the claim may still be valid, such as protective work clothes or uniforms that could also be used for personal use.