take your thermals ! or a good sleeping bag :-) you should be ok it gets dark by 7pm so take a good light, if you have not got all season sleeping bag , just buy a fleece liner, and have a good time :-)
We're camping at easter for the first time this year too, camped a few times in the summer last year. Think we'll just be going prepared for every type of weather, we'll get the stuff in somehow i'm sure
Long underwear, including some for under your pyjamas. A hat that won't come off in the night, although if you have company (I'm solo!) you might worry about looking this stupid! A wool blanket for under the airbed, a hot water bottle and at least one more layer than you think you will need - although that may just be me! A fleece and some warm socks and an extra blanket in the inner tent in case - there's nothing worse than waking up freezing and having to hunt for a blanket! I camp in January and I feel the cold, so if I can manage, anyone can!
Go for electric hookup and take a fan heater with you central heating in a tent,
if this is not possible take plenty of warm clothes and extra blankets a blanket under the airbed makes a big difference,i,m sure you will survive and have a great time and no you don't need your head examining were going at easter as i'm sure hundreds more will, have fun and enjoy yourself i'm sure you wont be the only one.
Everything Bluebottle said, especially the hat and the hotwater bottle, id also take your quilt as well if you can fit it in, and a hot drink before bed ( Brandy and hot chocolate for me )
Have a rug or a blanket on the floor next to your bed, cos there's nothing worse than stepping out onto a cold ground sheet when you get out of bed If you have enough space in the car to take a rug to put in front of your chair in the living area, it would probably help to keep your feet warmer, but the bedroom rug is more important in my opinion. We cover the whole floor of the sleeping pod with one of those fake fur rugs & it's lovely to step out onto - if it's extra cold we could pull it up across the top of us too!
For cold camping we take thermals and army socks ( green ones ) from army surplus. Our wonderful closing/locking barrel BBQ £20.00 from woolies close it up pop it on a metal tray and bring it inside. ( be mindful of the risk ) although we ve never had any problems and we have 2 large teenagers, and Old fashioned hot water bottles. The best thing really is to snuggle up closely and little too much booze.
Enjoy, we do what ever the weather. Getting excited its camping time!!!! YEAH.