Start with the tide table, not the weather app

Before you check whether it will be sunny, check what the tide is doing. Tide times are the single most useful piece of information for a UK beach day, and they change every day by roughly 50 minutes. Look up the times for the exact beach you plan to visit rather than the nearest large town — estuaries, headlands and long sandy bays can differ by half an hour or more, which matters more than you would think when you are walking out towards a distant sandbank.

As a rule, aim to arrive two to three hours either side of low water if you want space to spread out, shallow paddling and rock pools to explore. If you are visiting a beach with a steep shingle bank or a shelving sandy slope, high tide can leave very little room to sit, so a falling tide is usually the friendlier option.

The tricky days are the spring tides, which arrive around the new and full moon and produce the biggest range between high and low water. On those days the sea can move across flat sand surprisingly quickly, so keep an eye on fixed landmarks — a groyne, a slipway, a particular rock — and move your belongings up the beach before the water reaches them rather than after.

Pick a beach that works for your family

Not all beaches suit all families. A quiet cove with no facilities is wonderful with older children and a nightmare with a toddler, a picnic and no toilets. Think honestly about what your group needs.

• Lifeguarded beaches in peak season are the best default for families with children who want to swim. Lifeguards usually patrol from late spring through to early autumn, and they mark the safest swimming area with red and yellow flags.
• Sandy, gently shelving beaches are easier for little ones than steep shingle, which drops away quickly and can be painful underfoot.
• Facilities matter: check for parking, toilets, a café and, if you have a pushchair or wheelchair user in the group, whether there is a level promenade or a beach wheelchair scheme.
• Check dog restrictions if you are taking a dog; many beaches ban dogs between May and September, and some allow them only early in the morning or late in the evening.

Also check the car park situation before you leave. Some coastal car parks fill by 10am on a warm Saturday, and a few rural ones still take coins only, so keep a small amount of cash in the glovebox just in case.

Pack for four seasons in one day

A British beach day can involve blazing sun, a stiff onshore breeze and a sudden shower within an hour. Pack for all three.

• Sun cream at SPF 30 or higher, applied before you leave and reapplied every two hours — more often after swimming or heavy paddling. UV can be strong even under thin cloud, and the sea breeze makes it easy to miss.
• Layers: fleeces or hoodies, plus a lightweight waterproof, for everyone including the adults who insist they will not need one.
• A windbreak or small tent, which gives shade for naps and shelter if the wind picks up.
• Sun hats, sunglasses and a wetsuit or rash vest for children who plan to spend hours in the water. UK sea temperatures rarely climb above the mid-teens Celsius even in August.
• Water shoes for pebbly beaches and rock pooling, and a spare bag for wet kit.
• Water, snacks and a refillable bottle — dehydration on a windy beach creeps up on you.

Keep everyone safe in and near the water

Swim where the lifeguards are, and between the red and yellow flags. If a beach has no flags and no lifeguard, treat swimming as a serious decision rather than a casual dip: go in with someone else, stay in shallow water, and keep children within arm's reach at all times.

Cold water shock is a real risk on even a warm August day. Enter slowly, let your body adjust, and use wetsuits for children who will be in and out repeatedly. Teach older children what to do if they are caught in a current: don't fight it, stay calm, float on your back and raise one arm to signal for help.

Inflatables are best left at home on the coast. Offshore winds can carry them out in minutes, and they are involved in a large share of coastal rescues.

Plan the walk before you set off

A seaside walk is often the highlight of the day, but coastal paths are more demanding than they look. Check the distance honestly, allow roughly an hour for every two to three miles with young children, and pick a turning point so you can cut the walk short if the weather turns or legs get tired.

Wear shoes with grip rather than flip-flops, keep well back from cliff edges — the ground can be undercut — and supervise children and dogs closely near any drop. Tell someone where you are going and roughly when you expect to be back, and carry a charged phone, water and a snack. If you are walking a tidal causeway or crossing to an island, check the safe crossing window and leave a generous margin on both sides.

Food, fuel and a calm departure

Eat before everyone is ravenous, and aim for easy, sturdy food: sandwiches, pasties, fruit, and plenty of water. If you are using a barbecue, check whether the beach permits them — many do not — and never light one on dry dunes or shingle.

Finally, build in a wind-down half hour. Rinse sandy feet, change into dry clothes, gather everything and do a sweep of your pitch for litter, bottle tops and stray socks. Leave the beach as you found it, check the tide one last time as you go, and the drive home will feel far shorter than the drive down.