Probably the most frequently asked question at this time of year is "Are motorway services open on Christmas day?"
The short answer to that is YES. All motorway service areas must be open for fuel, parking, toilets, hot drinks and food 24 hours a day, 365 days a year - including Christmas Day, Boxing Day, New Year's Day and every other bank holiday. This is a condition of their licence, so there's no choice about it - they have to provide these services. If you're travelling on Christmas day, then you will be able to buy fuel at any motorway service area en route.
But... If you're planning on having Christmas dinner at a motorway service station, you may be disappointed. The requirement to provide food and drink doesn't extend to having all the facilities open, and you may well find that all you've got available is a selection of pre-packaged sandwiches and a coffee vending machine or a burger bar staffed by whoever drew the short straw this year. For MSAs that have a "mirror" configuration, with separate facilities either side of the motorway linked by a bridge, only one side may be open for food and drink and you'll need to walk across in order to use it if you park on the other side. At really quiet times, the licence requirements can be met by just the petrol station kiosk (providing it sells food and drink), so you may not even have a place to sit down. Equally, the retail facilities may well be partly or completely closed, so don't rely on using the MSA to pick up any last minute presents!
Also, the licence requirements only apply to "official" MSAs - the ones that get a blue sign on the motorway telling you about them. Some of the service areas listed on this site are not true MSAs, they're just MSA-like facilities near motorways or on non-motorway primary routes (such as Cambridge Services on the A14 and Grantham Services on the A1, or Leicester Markfield which is at J22 of the M1 but not signposted from the motorway), and there is no guarantee that these will be open on Christmas Day. If necessary, check with the operator before travelling.
Are you going to be visiting a motorway service area on Christmas day? Or maybe you work there, and you'll be on shift that day. We'd really love to get some photos taken at MSAs on Christmas day - why not send them in?