The twice we,ve been, we,ve been coming from a ferry. We bring casual clothes, our own pillow each books, playing cards, scented candles, makings of a home spa and relaxing baths for dd and I, swim gear. We have portable DVD for the car, but it works fine indoors too and a stack of DVDs.
We do a grocery shop after the ferry before arrival, enough for half the week and all breakfasts, bottle of gin, tonic, lime, wine, and a few treats.
I also bring a corkscrews sharp small knife, small chopping board, tea towels, oven gloves, matches, night lights, and a box of ice making bags, and another of freezer bags for snacks in the backpacks. A metal plunger coffee pot. A small bottle of washing up liquid, a handful of dishwasher tablets. Whatever sugar, salt, pepper and ketchup sachets I've gathered over the weeks beforehand, a small bottle of olive oil.
I look on it as a way to get out into fresh air, raincoat and runners are essential. We ignore the rain mostly, dd loved stomping on molehills in Sherwood. Make time for long hot soaks in early evening while dd is entertained by TV after long swim to wear her out. We generally book things after we get there but got to do what we wanted. We tend to eat in more than half, but probably had a meal out at least every second day (mostly lunch OR dinner, odd Starbucks coffee but never 2 main meals the same day). We took some snacks to pool so didn't,t have to buy there, but could if we wanted. We rented bikes, it's very easy to get around.
It can be relaxing if you allow it to be and don't expect too much of it. Pool can be nice, but occasionally busy, go early or quite late in the evening. Wildlife is lovely, and walking in woodland. Just kick back in the lodge, with a book or board game. Do a few activities. Go offsite if you want, we planned to but never did.