I agree that coastal retreats in Northumberland are excellent.
We want at least the same facilities as at home, even if smaller cottage.
Not basic, for a UK stay it is usually an add on to our main summer holiday,so I don't want to go somewhere that isn't lovely. Especially as the UK weather is so mixed, you can be in the cottage more than abroad.
I want somewhere I curl up with a book after a walk in February that is warm and comfortable. Otherwise I may as well do day trips from home or weekend small hotel stays.
So,
Dishwasher and well equipped and maintained kitchen
Bathroom and ensuite with decent spec.
Wi-fi
If aimed at more than 5 days stays,I want a washing machine and tumble drier.
Freeview and dvd player with films,but we had sky tv with films and a wii/ playstation at our coastal retreats cottage and this was a real treat in evenings for the children, especially when weather not great.
Outside space to play and sit,preferably with some play equipment such as bats and balls (well maintained and kept neatly) and a lovely garden or good view.
Parking outside.
Must be stylish, well decorated definitely( doesn't matter if ikea stuff added in, as long as it looks well put together not 'fussy') and immaculately,clean. No fusty smells.
Quality, cotton bedding and frequently replaced clean mattress - I always check.
Comfortable sofa for reading, with logburner if a winter stay.
Facility to arrange online food delivery for arrival and a small 'welcome pack' of milk, eggs,butter,jam,bakery bread,cake and wine.
Spotless, soft towels.
Dishwasher tablets, loo roll, hand soap, washing up liquid in enough quantity to last for a short stay of less than 5 days.
3 bedrooms, so grandparent can come.
Near a small village/ town for eating out, food shopping.
Beach optional, as we often go for countryside. Interesting area with places to visit and good pubs for eating are a must though.
We prefer to pay more and share holiday and cost with grandparent.
I wouldn't normally go for anywhere with a closeby river with young children, although the fenced off area sounds a possibility if it is large enough. A boat is great for parents with older children.
The 5 star cottage market, but equipped for families is the way I would go if I was buying a cottage. These places are always booked well ahead, and people return visit which saves costs in terms of marketing.