Within the six weeks, not every week carries equal demand. The two or three weeks either side of the August bank holiday and the very start of the school break are typically the busiest; the middle fortnight, particularly a normal midweek stretch rather than a weekend changeover, is often slightly easier to book and can be marginally better value. If the dates are flexible at all, a week in the middle of the school break rather than right at the start or the bank-holiday end tends to mean a calmer park.
For more detail, see dog-friendly caravan holidays.
Traffic is the other predictable factor. The Friday afternoon and Saturday morning before a bank holiday weekend are consistently the busiest times on the road network heading toward the coast, and the Monday afternoon return trip mirrors it in reverse. Travelling a little outside those windows, a Thursday evening arrival or a Tuesday morning departure where possible, avoids a meaningful chunk of that congestion for very little extra cost in time off.
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-holiday 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.
The two May bank holidays also work well as shorter breaks in their own right, for anyone who doesn't have a full week free. A long weekend built around the early May Monday, arriving Friday and leaving Tuesday, gives four days without touching much annual leave, and traffic on the roads tends to be lighter than the equivalent August bank holiday weekend.
For any family with children still at school, the calendar rules the holiday plan long before anyone opens a brochure. Term dates fix the weeks you can actually travel, and those same weeks are the busiest on every UK holiday park's booking sheet. The six-week summer break, the week around half-term in October and February, and the fortnight either side of Easter all draw the same crowd at the same time, which means the popular pitches and the best-value weeks go first.