So before you start thinking "Ooh! London! That's not far! let's go there!" I'd like you to remember that many, indeed all, of the putative 'attractions' are not only wildly disappointing when you actually get down to it, they're also ruinously expensive.
Now, the unequalled joy of sunning yourself in your garden and sucking down a cold beverage isn't absolutely free, but the expenses engendered (mortgage/rent, TV licence to cover use of radio, six-pack of Heineken mini-kegs) are ones you would bear irrespective of whether you fall into the holiday trap or not.
Something to think about, I'm sure you'll agree.