I make up a hamper for my son every Christmas, try the Ocado website.
If you search on the name of a slightly more unusual spice/sauce, say "rose harissa" you can see which aisle or shelf it is listed on and then take a general look at that shelf. I also buy some of the more expensive pastas, balsamic vinegar, oils, flours, nuts etc., a big bottle of good olive oil, good anchovies and sardines, crystal salt, interesting pepper and chipotle paste.
Waitrose have slightly less choice and tend to sell just their own version called "Cook's Ingredients" which I don't find quite so good.
Lidl do a lot of more luxury food items at Christmas: pink Himalayan salt in a grinder, little vacuum jars of pate or anchovies and so on, very attractively packed.