The embassy operates within the UK and must respect British laws, but the UK authorities have limited rights to enter the embassy premises or exert jurisdiction over those premises without permission from the embassy's country (Iran, in this case). For criminal matters or serious breaches of law, the host country and the embassy's country typically engage in diplomatic discussions to resolve the issue.
For example see Saudis killing journalist in their own embassy. Who was punished? Nobody, because it is Saudi's territory
https://en.wikipedia.org/wiki/Assassination_of_Jamal_Khashog...
EU regulators or Apple?
There's nothing arbitrary about EU creating regulations to protect its citizens.
However, the land on which an embassy is situated remains under the sovereignty of the host country, not the country that the embassy represents. The host country retains ultimate control over the land, although it must respect the embassy's independence and immunities. Diplomatic premises are subject to the laws of the host country to a certain extent, but with significant exceptions that allow the embassy to function as a representation of its home country's government.
The answer to your question is no.
I can't find anything here [0][1] which implies that embassies are foreign soil. I believe, for example, that if, hypothetically, a woman were to give birth in a US embassy they would not become a US citizen.
[0] https://legal.un.org/ilc/texts/instruments/english/conventio...
[1] https://fam.state.gov/FAM/08FAM/08FAM030101.html#M301_1_3