You probably wouldn't get much sleep in a service station, there's too much coming and going, even overnight, and especially the lorries. And you may well have to park up in the lorry area, depending on the service station. Refrigerated lorries have their chillers going, which can be quite noisy too. The few times we've stopped overnight in a service station I've had hardly any sleep, both because of the noise and being nervous about the possibility of someone trying to break into the car or van (just my overactive imagination, probably!). As Jonny says, it would be better if you could tell us whereabouts you want to stop - just the county would do, you don't need to be too specific! lol.