Another vote for Filey, North Yorkshire. Or Southwold or Aldeburgh in Suffolk, Wells in Norfolk. All seaside resorts with little shops and cafes/restaurants without being too commercialised x
Look at places along the river crouch we’re a very small area in essex which isn’t very touristy but we do have some nice restaurants overlooking water
Sorry to hear about your Auntie. She is very lucky to have such a lovely thoughtful niece. I am not sure where your Auntie lives but I highly recommend Southwold (Suffolk) for a little coastal break. Or up north my dad used to love visiting Robin Hoods Bay near Whitby when he was alive before cancer took him from us. Good luck with your search and get making memories x
Anywhere from hunstanton right up to cromer, there are some lovely air bnbs and hollday let's around that area somewhere like brancaster/Holme / Thornham and you can literally just follow the coastal road right along the norfolk coast.