The 20-year-old – who will compete in the 200m medley in London – was back down at the Aquatics Centre earlier this month for a training camp with the rest of the British team including double Olympic champion Rebecca Adlington.
Allen will be one of five members of the Olympic team heading to Hungary to compete at the European Championships in Debrecen next month but London will be her first meet with a full senior team.
But she insists the big occasion will not get to her when the Olympics roll into the capital.
“The British Gas Championships were really good, I have had a couple of years where I have been a bit off colour through injury and other reasons,” said Allen.
“But I trained really well and did lots of personal bests and got an Olympic place so it was all good for me.
“The camps are really good because it gets the team together and we can do loads of team building and get to know the team really well.
“This is my first senior team so I don’t know a lot of the others so it is really good seeing everyone and getting some really good training in.
“My training plan is pretty similar to what I have been doing at the British Gas Stockport ITC the rest of the year.
“It is just hard training and I will be going to European long course as well but that is it really – just hard work.
“It is very exciting that it is only 100 days away but I am trying to keep calm because if I get too excited I might get distracted from what I need to be doing. So I’m working hard now and I’ll get excited a bit closer to the time.”
Allen trains alongside Beijing open water silver medallist Keri-Anne Payne and three-time Commonwealth champion James Goddard in Stockport.
And she admits her experienced teammates have played a major role in helping her achieve her Olympic dream.
She added: “Competing at a home Olympics is not even a once in a lifetime opportunity, a lot of people won’t get this opportunity to be part of it.
“Training at the Stockport ITC is really good, we have the experience of Keri-Anne Payne and James Goddard leading the way for us.
“The British Gas Championships were at the Olympic pool and it was great to be at that. I was buzzing afterwards.
“The support I have had has been great, I have had so many cards and flowers and it is great to know everyone is behind you.”