Great Britain isn't a place where there are any active volcanoes but there are some igneous features found in the area.
The main features are Batholiths, Dykes, Sills and other intrusive features.

The best known Batholith is probably Goat Fell on the Isle of Arran in Scotland.

There are also a series of Dykes found here as well.
The Dykes are between 2 and 3 meters wide.

But how are they formed?

Oh right, sorry about that.

A batholith is like a magma chamber of a Fissure volcano that has that has cooled and solidified underground.
A dyke is a vertical column of igneous rock that is attached to the batholith, like the main vent of a volcano. Again the magma solidified intrusively.
Finally the sill is a row of igneous rock that is usually attached to the dyke and forms in the same way.

What can I say is that the view is so soothing to the eyes. Well, are such depend on the status of the volcano, probably active or dormant?

Extinct, because all the magma cooled to form the batholith, dykes and sills.
It was more of a magma chamber than an acctual volcano, I think.