Betfair have the awkwardly titled Burst Santas's Sack, a daily offer whereby you simply click on the game and hope to win a prize - free spins or something https://promotions.betfair.com/burst-santas-sack
Gala Bingo - have a set of 12 days of xmas offers at http://www.galabingo.com/promotions/bingo-promotions/advent-2014
Some risk free if you match a bet off at Betfair, some not - also watch out for the offers that reward you with Buzz points
(1000 can be converted into £1)
Foxy Bingo - have useful free offers throughout the year , but even more so at xmas http://www.foxybingo.com/members.php
They have offers each day in Dec, several of which are click to win offers which can give you 50p to £1 rewards for no risk.
Sky Vegas Not had much risk free from these so far in Dec, but worth checking daily: https://www.skyvegas.com/promotions/Christmas-Stocking
Tombola - These have their annual advent offers- you need to click the offers daily to optimise chances of winning. Also remember to withdraw your real cash before accumulating bonus cash to stop real cash being spent before you turn over the bonus.
Mr Green -Advent free spins (25 or 50 daily) if you have deposited in the past week, again withdraw real funds is recommended before aquiring bonuses:
Unibet - Daily offers https://www.unibet.co.uk/promotions/advent-calendar (these can be slow to credit bonuses,)
Betvic - Not much of interest here since the first week in Dec but http://www.betvictor.com/sports/en/content/betvictor-christmas-advent-calendar
NetBet - Daily prizes to win -electronic devices etc https://sport.netbet.co.uk/advent14/
Coral - Fancy little xmas animation likely to be a few worthwhile offers: http://promotions.coral.co.uk/christmascoral/
William Hill - http://vegas.williamhill.com/promotions/vegas-games/spin-to-win/ Daily free spin of their offer wheel (found on the front page right hand side) The banner appears between 6pm - 7pm ,9pm - 11pm. Free Spins, Bingo bonuses and risk free £10 ers on Live Casino amongst the prizes
188bet - Daily offers from the 12th Dec to 25th http://www.188betpromo.com/UK/12D-XMAS/ Always note down the offers you have done in case you need to prompt them.
Remember: Keep It Risk Free