It is worth checking the cancellation and amendment terms attached to your specific rate before you commit, particularly if the weather or a specific event date matters to your plans. Terms vary between a flexible rate and a non-refundable deposit rate, and the booking page should say plainly which one applies to the price you are looking at.
If you plan to do this trip regularly, contacting the park directly to ask about the walk or transport link from the nearest station is worth doing before you book, since staff who deal with this question often will know the practical details, such as which taxi firms are reliable locally, better than a general search will tell you.
Taking the dog on a UK holiday-park break is common enough that most parks have a clear pet policy, but the details are worth reading properly rather than assuming every park works the same way. A limit of one or two dogs per booking is typical, and it is one of the first things to check if you are travelling with more than that, since a park with a strict two-dog cap will simply say no at the door rather than bend the rule on arrival.
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.
Where parks differ most is on linen and towels. Some include bed linen as standard and simply ask you to bring your own towels, others include both, and a smaller number charge a linen hire fee if you would rather not pack your own bedding. It is one of the first things worth confirming when you book, since turning up without towels because you assumed they were provided is an easy mistake to make.
See more on this at static caravan holiday lets.