A Solitary Pursuit?

It's a familiar cliche to say that the life of an author is a solitary one, stuck behind a desk typing. But what about those of us who struggle to find a quiet spot in which to write? Not everyone enjoys the luxury of an empty house - or even a private study.
My husband helpfully remarked recently that we have a decent sized garden shed, large enough to house a table and chair. By dint of pushing the garden tools right up against the wall, stacking spare plastic chairs in one precarious pile, and engaging in a battle with the lawnmower, it could be done. The shed even boasts the benefit of a small skylight to admit natural daylight. With the faint glow of my screen, that could be workable. But I'm not sure I fancy spending hours with spiders and garden sheers, especially as I have just (ficititiously!) battered a poor man to death in his garden shed. I should add that this scene was written BEFORE my husband's suggestion!
I do have a very nice desk in the house, complete with comfortable chair, and bookshelves spacious enough to house a copy of every edition of all my books, including all the editions in translation, and more in hardback and large print... Now I come to think of it with two books coming out a year from now on, I'll soon be needing more bookshelves.
   The trouble with my very nice desk in my quiet study is that with three other people living in the house, all under strict instructions not to disturb me when I'm writing, there is usually someone bringing me a cup of tea, and then of course they stop for a chat.
The easy alternative is to go out to a local cafe - but then I'm often accosted by a local friend and yes, they stop for a chat.
And when I am left to my own devices, there are my friends and contacts online: facebook, twitter, and my blog.
So I guess it's me... It's a wonder I get any writing done at all!