The pattern is consistent enough to plan around. Demand for the specific bank holiday weekend itself, arriving Friday or Saturday and leaving Monday or Tuesday, is noticeably higher than for an ordinary weekend either side of it, since a Monday off turns a normal two-night stay into a three or four-night one without using annual leave. That means the actual bank holiday dates are usually the first to book out, while the weekend immediately before or after often has more availability at a similar price.
A weekend suits a short window: a bank holiday, a gap between other commitments, or simply not having more than a couple of days free. It works well for a couple, a pair of friends, or a family who just want a change of scene without the planning that a longer trip demands. Arrive Friday evening, get one full day and a morning, and you're home by Sunday teatime having barely touched the weekly routine. The travel-to-self-catering holiday parks ratio is the thing to watch: if the drive to the coast takes three hours each way, a two-night stay leaves less actual time there than the driving took to get there, so a weekend break makes most sense somewhere within a couple of hours' drive.
Booking early is less about beating a queue and more about choice. A pitch with a sea view, a caravan that sleeps six comfortably, or a week that lines up with both parents' annual leave: these are the bookings that get taken months out, not the week before. Parks along the English coast, ours included, tend to open the following year's summer diary not long after the current season closes, so the families who book in autumn get first pick of the following July and August.
Summer is the busiest season on the UK coast by some distance, and the six weeks of the school holidays carry the bulk of that demand into a single stretch of the calendar. Planning around it well is less about avoiding the crowd, since a summer break inevitably means one, and more about timing and expectations so the busy weeks work in your favour rather than against it.
A couple wanting a quick reset and a family planning their main holiday of the year are, in practice, choosing between two different kinds of trip, even if both end up in the same caravan. Understanding which one you actually are makes the choice easier.
Both half-terms fill up faster than an ordinary week because every school in the country breaks up at roughly the same time, so the whole country's families are looking at the same seven days. Booking two to three months ahead gives the best choice of pitch and accommodation type; leaving it to the fortnight before means taking whatever's left, if anything is.