The Foreign and Commonwealth Office (FCO) advise against all travel to:
within 100km of the entire Iran/Afghanistan border
within 10km of the entire Iran/Iraq border
the province of Sistan-Baluchistan
the area east of the line running from Bam to Jask, including Bam
British nationals, in particular dual British/Iranian nationals, face greater risks in Iran than nationals of many other countries, including the risk of arbitrary detention. The Iranian authorities don’t recognise dual nationality for Iranian citizens and therefore don’t grant consular access for FCO officials to visit them in detention. You should consider carefully the risks of travelling to Iran. See Safety and Security
On 24 and 25 June 2018, protests about the economic situation in Iran took place inside and around the Grand Bazaar in Tehran. There were also widespread protests across Iran in late December 2017 and early January 2018. The risk that these protests re-occur or new demonstrations begin on other grounds, remains. You should exercise caution and avoid any protests or rallies and follow the instructions of the local authorities.
As of 15 April 2018 bureaux de change are not licensed to trade currency. It is illegal to change money on the street. You should be clear before travelling how you will obtain enough rials for your visit legally and, if unsure, you may need to reconsider your travel plans. See Money
Terrorists are very likely to try to carry out attacks in Iran. Attacks could happen anywhere, including in places visited by foreigners. On 7 June 2017, there were 2 attacks in Tehran – one in the Majles (the Iranian parliament) in central Tehran and another at the Imam Khomeini Shrine near Imam Khomeini international airport. See Terrorism
Iran is a Muslim country in which Islamic law is strictly enforced. You should respect local traditions, customs, laws and religions at all times and be aware of your actions to ensure that they do not offend. See Local laws and customs
British nationals need a visa to travel to Iran. You should make your visa application well in advance of your date of travel. The application process for an Iranian visa can be long and unpredictable. The Iranian Embassy has told the Foreign and Commonwealth Office that to get a visa you must either apply as part of an organised tour, or have a sponsor in Iran. See Entry requirements
Take out comprehensive travel and medical insurance before you travel.