What generally does stay open regardless of season includes reception, essential maintenance and emergency contact arrangements, along with any general shop or laundry facility, though even these can run to shorter daily hours in quieter months.
See the details at Norfolk Broads holidays.
For families, items like a travel cot, highchair or stairgate are sometimes available to hire from the park rather than something you need to bring, so it is worth asking at the booking stage rather than packing something bulky that duplicates what is already on site. The same goes for pet supplies. A food and water bowl is sometimes left in pet-friendly units, but pet food, a lead and any bedding for your dog are down to you.
Next, look at what the quoted price includes. The headline rate usually covers the unit itself, but bed linen, towels, a travel cot, or an early check-in slot are often charged as extras rather than bundled in. If the listing does not spell this out clearly, a quick call to the park office before booking is worth the two minutes it takes.
Parking is another practical detail. An accessible unit is generally allocated its own parking bay close to the door, but it is worth confirming the actual distance rather than assuming, particularly if a longer walk with luggage would be difficult.
If you are booking with a dog for the first time at a park you have not used before, a short call to ask „how many dogs, any restrictions, and what is the fee“ covers the three questions that matter most, and means the policy is confirmed in your own words rather than assumed from a general holiday-park norm.