"It would be huge for us to qualify on Wednesday. Holland are the only other (European) team to qualify so far. The quicker we do it the better," Terry told reporters.
"We would give ourselves a lot of time with friendlies and qualifying games for the manager (Fabio Capello) to try different formations, different players before the World Cup.
"If we can get there we can really relax and enjoy our football going into the World Cup."
Terry, speaking before Saturday's friendly with Slovenia, said the players wanted to qualify as soon as possible and would fine-tune their preparations in the warm-up game at Wembley.
"It's difficult not to think about (the Croatia game on) Wednesday but the manager has emphasised the game on Saturday to get the best out of Wednesday," he said.
England lost 3-2 to Croatia on a rainy night at Wembley in November 2007 to miss out on a place in Euro 2008 but won 4-1 in Zagreb a year ago, one of their seven successive World Cup qualifying victories in Group Six.
If they make it eight out of eight on Wednesday, they will be sure of their place in the finals.
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"It was a disappointing night the last time they (Croatia) were here and that is in the back of our minds. But we don't go in with a revenge mentality," said Terry.
"It's a chance to put things right where we left off last season."
Terry also praised the form of Tottenham Hotspur striker Jermain Defoe who has made a superb start to the season scoring four times for his club and twice for England so far.
"He is probably pushing to be the No.1 or No.2 striker at the moment," said Terry.
"I hope he carries on scoring goals for England, not for Tottenham," he joked.
Capello said all his players were fit and trained on Friday, apart from Manchester United goalkeeper Ben Foster who had returned to the north-west where his partner was due to give birth.
"Good luck. He will return in the evening and will be ready for the game," Capello said.
"We haven't spoken about Croatia, we had a meeting on Thursday but we spoke about the game against Holland and the mistakes (in last month's 2-2 friendly draw). On the (Friday) evening before the game we will speak about Slovenia."
