Second point: An employer is free to determine which days their employees take their statutory holidays, as long as they give reasonable notice. So, if you knew at the start of the year that the firm would close for 2 weeks over the Christmas period your employer could designate those 2 weeks as 10 days of your paid holiday. Then you'd have been left with just 11 days (because of the new rules, as above) to 'play with'. However, your employer could have also designated other works closure days (e.g. the 5 public holidays which occur outside of the Christmas and New Year period) as part of your statutory holiday, so you'd have been left with perhaps just 6 'flexible' days.
If you were pre-warned that you were meant to include the Christmas period in your statutory holiday entitlement, the employer has every right to refuse to pay you over Christmas since the days off you'll be having are just the same as if you'd asked your employer for additional (unpaid) holiday during the summer period
However, if you were not pre-warned that you must include an extended Christmas period in your holiday calculations, the situation is different. The employer is effectively 'laying you off' for 2 weeks. If so, it's likely that you should still be paid. See here:
http://www.direct.gov.uk/en/Employment/Employe es/RedundancyAndLeavingYourJob/DG_10026693
For further advice, phone the ACAS helpline on 08457 47 47 47 (0800-1800, Mon-Fri).
Chris