The 19-year-old, who made his debut against Liverpool at the Lane towards the end of last season, travelled to La Manga for the training camp and played the first half of the 2-0 friendly win over Stevenage on Wednesday evening.
"It's been good," said the striker of his training stint with the seniors. "Tiring, but enjoyable.
"It gives you a big lift to have such good players around you. It seems you can get away with more in terms of trying different things on the pitch and they talk to you and help you - it is much better."
Preparing for the season under the watchful eye of Glenn is an added incentive for the now 6ft 2" Jamie, who know that good displays or goals in training will be noted by the manager himself and not just reserve boss Colin Calderwood.
"Colin would tell him anyway if I did score a beauty - hopefully. The gaffer knows what I'm capable of and just wants to get the bad things out of your game so you can improve all the time.
"The gaffer encouraging me and is always telling me to listen to the coaches and pro's around you who will always help."
Jamie Slabber says that preparing for the new season with the first team squad has been a major boost for him.