The phrase "a few extra blocks" is correct and usable in written English.
It can be used when referring to a small additional distance or number of blocks in a city or urban area, often in the context of directions or travel.
Example: "The restaurant is just a few extra blocks down the street from the subway station."
Alternatives: "a couple more blocks" or "a few additional blocks".
She figured she could walk from there, a few extra blocks.
There is much talk of a long-planned Second Avenue subway, but now residents have to walk a few extra blocks east or creatively utilize city bus routes.
When consumers have become involved, they have done so mainly at the gas station, by buying regular rather than premium gasoline, for example, or by driving a few extra blocks in search of cheaper gas, particularly in California where it often tops $2, or by vacationing closer to home, or by leaving the S.U.V. in the garage and driving the family's more fuel-efficient second car.
The presence of a few extra officers down the block, it was thought, wouldn't make much difference.
We actually circled the block a few extra times that day.
Cover up with sun-protective clothing and a wide-brimmed sun hat and take a few extra minutes to apply broad-spectrum UVA/UVB-blocking sunscreen containing titanium dioxide, zinc oxide or avobenzone.
DNA is essentially composed of 4 building blocks that are at best modified with a few extra side bits here and there.
(Currently, the iOS app has a few extra features compared with the Android version, including this ability block users and delete comments).
Sometimes, they actually can be fairly handy, if you need to get a few blocks faster than your legs can carry you (and you have a few extra dollars in cash burning a hole in your wallet).
My anger turned to disgust when I realized that someone like my sister who required handicap parking would have to park blocks away just so some fat, tanned asshole doesn't have to walk a few extra feet.
