You will need a visa to pass through the UK to Ireland unless you are exempt. You usually need to apply for a regular visitor visa.
The Common Travel Area (CTA): is an arrangement between the United Kingdom (UK) and Ireland that gives a variety of rights to citizens of those countries. It includes more than the basic right to travel freely between both countries.There are no normal passport restrictions for Irish and UK citizens traveling between the 2 countries.
Traveling without a visa You may be eligible to transit to Ireland without a visa if:
- You arrive and depart by plane
- You must have a regular onward flight departing before midnight on the day of your arrival or the day after your arrival
- Have the correct documents for your destination (for example, a visa for that country)
- You must have an Irish biometric visa (marked 'BC' or 'BC BIVS' in the 'Remarks' section) and an onward flight ticket to the Republic of Ireland.
- E-Visas or e-Residence Permits are not acceptable for traveling through immigration control without a visa.
- All visas and residence permits must be valid.
- You cannot travel without a visa if a Border Force officer determines that you do not qualify under the immigration laws.
Traveling without a visa. You may be eligible to transit without a visa if:
- You arrive and depart by plane
- You must have a regular onward flight departing before midnight on the day of your arrival or the day after your arrival
- Proper documents for your destination (eg visa for that country)
One of the following may also be eligible for visa-free transit:
- You are traveling to (or as part of a reasonable trip to) Australia, Canada, New Zealand or the USA and have a valid visa for that country
- You are traveling from (or as part of a reasonable journey to) Australia, Canada, New Zealand or the USA and have a valid visa for that country
- You are traveling from (or as part of a reasonable journey to) Australia, Canada, New Zealand or the USA and it has been less than 6 months since you entered that country with a valid entry visa
- You have a permanent resident permit issued by Australia or New Zealand
- You have a general format residence permit issued by a European Economic Area (EEA) country or Switzerland
- You have a permanent resident permit issued by Canada on or after June 28, 2002
- You have a Uniform Format Category D visa for entry to a country in the EEA or Switzerland
- You have an Irish biometric visa (marked 'BC' or 'BC BIVS' in the 'Remarks' section) and an onward air ticket to the Republic of Ireland
- You are traveling from the Republic of Ireland and it has been less than 3 months since you were last authorized to land or remain in Ireland on the basis of holding a valid Irish biometric visa
- You have a valid USA Permanent Resident Card issued by the USA on or after April 21, 1998
- You have a valid USA I-551 Temporary Immigrant Visa issued by the USA (wet ink stamp version will not be accepted)
- You have an expired USA I-551 permanent resident card issued by the USA on or after April 21, 1998, and a valid I-797 letter approved extension
- You have a valid USA-issued US Immigration Form 155A/155B (enclosed in a sealed brown envelope)
- You cannot travel without a visa if a Border Force officer determines that you do not qualify under the immigration laws. If you are not sure whether you are eligible for transit without a visa you can apply for a transit visa before you travel.
Check if you need a UK visa: https://www.gov.uk/check-uk-visa
People with UK visas or residence permits
If you are a citizen of a country whose nationals need a visa to enter Ireland and you have a valid UK visa or residence permit, you may be required to have a visa to enter Ireland before you arrive in Ireland. The Short Stay Visa Waiver Programme allows nationals of a number of Eastern European, Middle East and Asian countries who have a short-term UK visa to come to Ireland without the need for a separate Irish visa.
Short Stay Visa Waiver Programme: https://www.irishimmigration.ie/coming-to-visit-ireland/short-stay-visa-waiver-programme/
Reciprocal visa arrangements: A British Irish Visa Scheme applies to visitors from China and India. This scheme allows visitors from these countries to travel freely within the Common Travel Area (in this case, Ireland and the UK but not the Channel Islands and the Isle of Man), using either an Irish or UK visa. British Irish Visa Scheme visas are endorsed with ‘BIVS’.
British Irish Visa Scheme : https://www.irishimmigration.ie/coming-to-visit-ireland/british-irish-visa-scheme/
READ MORE INFO: https://www.citizensinformation.ie/en/government-in-ireland/ireland-and-the-uk/common-travel-area-between-ireland-and-the-uk/