Umar Arshad, 24, was jailed for six years and nine months and Syed Farhan Hussain, 22, for five years and three months for their roles in preparing for the terrorist attack at a Territorial Army centre.
The men, all from Luton, admitted one count of engaging in conduct in preparation for acts of terrorism between January 1 2011 and April 25 2012 at a hearing on March 1.
The men were arrested following a series of raids at their homes in April last year after an intelligence-led joint operation by the Metropolitan Police Counter Terrorism Command and the British Security Service (BSS).
More top news
The 23-month-old continued breathing after life-support was withdrawn and doctors agreed to give him oxygen and water, his father said.
Prince Charles joked about not being able to keep up with his grandchildren.
Ahead of his meeting with Jewish community groups, the Labour leader vows to ensure anti-Semitism is stamped out.