In Finland, in a region where they have temps of -30°C, for months the central heating of several towns and villages was targetted by massive hacker attacks that prevented the central core installations from starting to work. For months. Quite a problem with -30° around you. They had to fall back to the dratsic solution of almost cutting all internet and computer wires into the network controlling these heatings.
As long as Britain does not cut the comourer and communicaiton wires leading from and to its island, all the talkign of the likes of "the continent looks for itself, Britain stays for itself" is pointless. Even more when considering that without said wires the British finance industry is toast.
During the 60s, 70s, 80s, any Sovjet invasion of NATO Europe would have been opened by a massive volley of nuclear atacks on NATO'S airfield and CCCI.network. Any Russian attack today would be opened with a massive Russian cyber-attack that already would have started months before the conventional military actions begin.
And the Geneva convention and Hague Convention never have had something like cyberwar on mind at all.
Its impossible for Britain to not care for the continent. Whatever happens on the continent, will find britain too. Geographic isolation does not have the same meaning anymore like it used to have.
Have a volley of EMP bombs shattering the fundament of modern civilization and taking electricity out of the equation - then we talk again.