The 21-year-old was playing student rugby with Loughborough University just a few months ago but with regular starter Chris Cusiter out with injury Henry has been thrust straight into action.
Henry told the Evening Times: “It is just an unbelievable turnaround from student rugby and I owe it all to Warriors coach Sean Lineen for giving me the chance.
“I had a trial with Glasgow before the end of last season, but you never take anything for granted until you make your debut.
“To be filling in for a world-class player like Chris Cusiter, who is one of the best scrum-halves in the world, and to face clubs of the stature of Sale and Wasps in my first two games for Glasgow, is really a bit of a dream.
“When I first started training with Warriors it was really tough.
“I was never one for going to the gym much when I was at Loughborough, but we are in every day.
“Between weight sessions, gym work and the training itself, I was in bits for a couple of weeks.
“But, increasingly, I have begun to feel more comfortable and started to enjoy the training – and the facilities at Scotstoun are first-class.
“I realise what a great opportunity this is for me and I am just determined to work as hard as I can to repay Sean and Glasgow for the chance I have here at Warriors.”
Meanwhile, London Wasps have named a strong line-up to face the Warriors in Saturday's friendly.
15 Mark Van Gisbergen
14 Richard Haughton
13 Ben Jacobs
12 Dom Waldouck
11 Tom Varndell
10 Riki Flutey
9 Joe Simpson
1 Tim Payne
2 Rob Webber
3 Phil Vickery
4 Simon Shaw
5 Richard Birkett
6 Joe Worsley
7 Tom Rees (c)
8 John Hart
Replacements
16 Tom Lindsay
17 Zak Taulafo
18 Ben Broster
19 Dan Ward-Smith
20 Serge Betsen
21 Nic Berry
22 Dave Walder
23 Jack Wallace
24 James Cannon
25 Sam Jones
26 Christian Wade