The honest caveats matter here more than in any other season. Swimming pools, outdoor play areas and some on-site catering at seaside caravan breaks parks typically close or run reduced hours over winter, and local seasonal attractions, ice cream kiosks, some smaller museums, often shut entirely until spring. Check what's actually open at your specific destination before travelling rather than assuming a scaled-down version of the summer offer; in some cases it's closed rather than reduced. Weather can also affect road conditions on rural approaches to the coast, so it's worth checking the forecast the day before rather than the week before.
Managing the day itself matters as much as the booking. Popular beaches and attractions near any coastal park get busy from mid-morning onwards in peak season; an early start for a walk or a swim, before the day-trippers arrive, is a straightforward way to get a quieter beach out of the same week everyone else booked. Evenings tend to thin out earlier too, once families with young children start winding down.
It isn't a like-for-like swap with summer, and it's worth being straight about that. Some seasonal attractions, ice cream kiosks and smaller cafes close for the winter altogether, so it pays to check what's actually open at your destination before you set off rather than assuming it mirrors the summer season. The weather is more changeable too: pack for rain and wind as a matter of course, not a possibility, and treat any sunshine as a bonus rather than an expectation.
For a couple, a short break, two or three nights, usually built around a weekend, does most of what's needed. There's no school-term constraint to work around, less packing, and less need to fill every day with an activity. A Friday-to-Sunday trip to the coast gives a proper change of scene, a couple of decent walks, an evening meal out, and time to properly switch off from work without using much annual leave at all. The travel time matters more here than for a longer trip: somewhere within two hours' drive makes the most of a short window, since a five-hour round trip eats into what's a fairly brief stay to begin with.
Wildlife and colour are the specific draw many people underrate. Migrating birds pass along stretches of the East Yorkshire and Norfolk coast through September and October, and hedgerows and coastal scrub turn properly seasonal colours a few weeks before inland areas catch up, thanks to the milder coastal microclimate. A pair of binoculars is a better packing decision for an autumn coastal trip than most people think to bring.
There's a practical side too. If your children are tied to term dates, travelling even a day either side of the official holiday means less competition for the roads and the local attractions, without losing any of the actual holiday. Leaving on the Saturday after school breaks up, rather than fighting the Friday afternoon exodus, can shave a good hour or two off a journey to the coast.