Irfan Raja's parents, who do not follow the teachings of radical Islam, were horrified when they found the note along with "a vast library" of Jihadist material on his computer and a desktop icon that played a song about martyrdom.
The note, which
was translated into English for the jury, read: "If not in this (world) we will meet in the (Garden of Paradise), Inshallah.
"The situation is such that you will live another 30 years, maybe 40 years.
"When death will befall you, maybe then you will appreciate what I have done now.
"At such times, there are parents in this world that would phone their families and friends and rejoice at the decision of their son."
After referring to several verses in the Koran he writes: "I think all of you will be upset, especially Ami-ji (mum).
"Please don't blame each other for why you couldn't stop me. It is better to spend time in praying to Allah."
He adds the postscript: "Just in case you think I am going to do something in this country, you can rest assured that I am not. The conventional method is safer."
Raja ends the note by warning his family to be careful the letter does not get into the wrong hands as "people (of UK] use everything against you".
Mr Edis said: "How do we know whether this was a series of adolescent fantasies or a purely academic interest?
"The defendant Irfan Raja left Ilford to join the Jihad on the 24th of February 2006.
"He was supposed to be at school that day – he was then 17 – but instead he went by bus, by prior arrangement, to Bradford where he was met by some of the other defendants.
"When Mr Raja went to join the Jihad he chose Bradford and his co-defendants who sit there by him in the dock as the best way to start. He had of course hidden his purpose from his family, who were, when they found out what he had done, absolutely beside themselves with worry and fear.
"Mrs Raja heard with horror the song written from the point of view of an Islamic martyr, that her son had installed on his computer desktop, and remembered a conversation they had the night before when he had "asked her for her forgiveness".
Mr Edis said: "They had noticed some signs of increasing religious observance in their son over the period leading up to this.
"They are a Muslim family and an observant Muslim family.
"They do not subscribe to this radical train of thought which leads people to go and fight in the Jihad."
After a tearful phone call Raja's parents persuaded him to return home, but by then anti-terrorist police had seized his computer. Among the documents collected by Raja and the others were "highly professional" films highlighting the suffering of Muslims, the court heard.
Alongside footage of the mistreatment of Muslim prisoners in Abu Ghraib prison in Iraq is the proposed solution – suicide bombs.
Terror plot accused 'had bomb vest instruction video'