Wot Donut said (all of it!)
Although it's difficult to generalise, because as with most countries different people prefer different styles, so there is quite a variety of interior design and furniture around.
Most people generally have carpeted floors and curtains, although wooden flooring and blinds at the windows are now seen as quite modern and are therefore popular with some people.
Is it possible for your boyfriend to get hold of any British magazines on interior design? There are a wide range to choose from, ranging from old fashioned farmhouse type style to modern 'loft apartment' minimalism.
You may find
this site useful - it's the website of the Geffrye Museum which is dedicated to British homes and interiors through the ages, from medieval through to the 21st century...