Any gifts in cash, vouchers, items readily convertible to cash or shares must be processed via your company payroll and are subject to PAYE and NIC. What that often means in practice is that the vouchers you hand out at Christmas are often worth a lot less to employees than you think, for higher rate tax payers a whole 41% less than you, or more importantly they think.
The qualified yes comes in the form of the ability for a company to arrange a PAYE Settlement Agreement with HMRC. In this case the employer can arrange to pay the PAYE/NI that may be due directly to HMRC rather than taxing the employees directly.
Gifts such as turkeys, hampers, chocolates, wine etc are not subject to the same rules. Instead these are classified as trivial gifts provided the value doesn't exceed £30 per employee. However, agreement must be obtained from HMRC to avoid the obligation to complete a P11D or to pay tax and NI.