Roy Hodgson's side face a crucial World Cup qualifying double header against Montenegro on Friday and Poland on Tuesday knowing two victories would guarantee them a place in the tournament.
England are top of Group H going into the Wembley matches and, despite feeling frustrated that their place is not already assured, Everton centre-back Jagielka remains upbeat about their chances of securing their qualification.
"Our aim was not to have to rely on favours coming into this week," he said.
"We would have liked to have got it done and dusted by now. That is not the case, but we are still looking at it in a positive way.
"If we can get the two results we need, and that is in our hands, we will be booking our flights to Rio.
"There are quite a few people with experience of being in similar situations and we also have some young lads with fantastic ability.
"We are all massively confident we can go out there in a packed Wembley and put on a good performance. Hopefully it will be an exciting couple of nights."
Ashley Cole misses the Montenegro game with a rib injury and is a doubt for the game with Poland.
But Jagielka is confident his club team-mate Leighton Baines will be a capable replacement, if he is chosen by Hodgson to fill in for Cole.
"A lot of people have said it's a close fight between the two to see who would start," added Jagielka.
"If that is the case and Baines gets the chance to start, I am sure he won't let us down.
"He is a fantastic defender and gives us an attacking threat down the left as well."
Despite his confidence, Jagielka is not taking the threat of Montenegro lightly, a team that have held England to three draws in qualifying matches and who are third in the Group H table, level on points with Ukraine and just one point behind England.
"They have got some players who play in the best leagues in the world," he said. "They have some very talented players, and as a nation they are progressing.
"They are still in with a chance to qualify themselves."