I'm looking for the title of a book that I read a few years ago that includes the following details/plot points:

1) The book is set somewhere in a major city in the UK (possibly London)

2) There is a snowstorm that begins to destroy the world (the first few days are described as being normal, before the snow begins to cover everything)

3) The main character is a South Asian (?) woman who has a daughter who converted to Islam to marry a Muslim man. The main character recalls her daughter becoming more and more devout.

4) The main character ends up stuck in a tall building with a builder (?) who is rationing the last of his cigarettes.

5) The characters seem unable to reach different floors of the building because of the snow and end up having to ration their food supply.

6) It is mentioned that the main character and the builder (?) have sex at a few points

7) The builder (?) gets a leg infection and eventually dies from it.

8) The South Asian woman is the only survivor at the end of the book.

9) I can't remember how the book ends although I think it may have involved aliens creating the snowstorm (?).

10) The book had a white cover and I think the title referenced "snow".

Thanks in advance.