I came across some great deals with Hotel du Vin for double rooms over the December/ January holiday period. Newcastle is the cheapest I found at £44 and most are at £49. These rates are non-refundable.

A few tips:

If you are booking via the Hotel du Vin site and you attempt to abandon the booking, you should get a pop-up asking you to continue the booking to receive a free glass of wine each ;p

Alternatively, most of the rooms seem to be available on hotels.com (which is where I booked mine), currently quoting £51 giving 12.12% cashback on topcashback for mobile bookings, reducing the cost by another 6 quid or so per room, reducing the price to £45. (I made my two bookings separately clearing cookies in between and both sets of cashback have already tracked).

I booked:
Saturday 17 December - three doubles at Poole for £45 each after cashback
Friday 30 December - one double at Wimbledon for £45 after cashback

Play around with the dates to see what you can find. I took a look through before posting this to check other dates I noticed at around £49 on the official site included:

Sunday 2 January (remember next day is a bank holiday) - Poole, Wimbledon, Tunbridge Wells, Cheltenham, Cambridge, Birmingham, Henley, Windsor, Bristol, Brighton, Harrogate, York. Newcastle is cheapest at £44.

Friday 30 December - Poole, Wimbledon, Birmingham, Winchester

Tuesday 27 December - Wimbledon, Birmingham

Wednesday 28 December - Poole, Wimbledon, Birmingham, Tunbridge Wells

Thursday 29 December - Wimbledon, Birmingham, Tunbridge Wells

Friday 23 December - Wimbledon, Brighton, Birmingham, Cambridge, York, Winchester, Henley

Saturday 17 December - Poole, Wimbledon

Note: if you require a twin room, the only hotel I saw with twins at the cheapest price was Brighton.

Hope this helps someone get themselves a nice Christmassy break!