It is accepted custom and practice in many industries for suppliers you have had contact with during the year to give gifts at Christmas. Unless there are specific clauses in your contract or Staff Handbook concerning the receipt of such gifts, this is probably acceptable, provided you act in your employer's best interests in all dealings with suppliers.
However it is wise to read the policy carefully and to make sure you follow it to the letter, and if you are in any doubt, to discuss the issue with your manager. Especially in the current difficult economic climate, it is important not to provide bad employers with an excuse for disciplinary action.
Some gifts may be deemed by the HM Revenue & Customs to be income and therefore taxable. In general, you should be honest and open about the receipt of all gifts.