The Oireachtas Foreign Affairs Committee has begun a three-day fact-finding visit to London.
The trip is to focus on Brexit, overseas aid priorities and engaging with Irish communities in the British capital.
Committee Chairman Brendan Smith is being joined by TDs Sean Barrett and Noel Grealish.
On Wednesday the TDs' first port of call is the All-Party Parliamentary Group on the Irish in Britain, chaired by British Labour MP Conor McGinn.
The afternoon features a series of meetings with the House of Commons' Foreign Affairs, International Development and Exiting the European Union committees.
Deputy Smith said: "Britain's impending move to leave the European Union provides the critical context for much of our discussion on the first day of the committee's trip.
"We must redouble our efforts to maintain close working links with our British parliamentary counterparts and ensure a high level of awareness and understanding of the significant challenges that Brexit poses for Ireland."
Chairman Smith added: "I also hope to discuss the many challenges facing the international community, not least the deeply troubling situation on the Gaza/Israeli border and the disproportionate use of force on unarmed protesters, a matter of grave concern for the committee."
On Thursday and Friday, the committee will meet a wide range of Irish community and cultural centres.
This will see engagement with the Irish Diaspora to address their concerns.