The game is the penultimate match of this season's WRU Colleges League, with both sides competing for a place in the Millennium Stadium final against Coleg Sir Gar on April 17.
Thomas' side may have home advantage, but know they will face anything but an easy ride against Morgannwg. And after watching his side impress in the competition so far, the Llandovery College head coach is hoping his side have what it takes to make it to the last two.
"It's a wonderful opportunity to play at the Millennium Stadium and one we don't want to let go," he said ahead of tomorrow's game.
"Should we be beaten it will be incredibly disappointing but if you had told me at the start of the season that we would end up in a play-off for a final, I'd have taken it.
"I was worried the tournament would be a big step for us but it's been wonderful for the college and has helped improve our squad and overall rugby. It's been brilliant."
Both teams have played some fluent running rugby to get them to the play-off and the match between the two colleges back in March was certainly one to remember.
It was Thomas' side who were winners that day, eventually running out 27-24 winners, and the Llandovery head coach is expecting tomorrow's play-off to be just as tight.
"It's going to be incredibly close, there's absolutely nothing in it," he added.
"Even though we are at home I would consider ourselves as underdogs. Morgannwg have got a number of rising stars coming through their ranks.
"It's going to be a stern test for us tomorrow."
One of those players coming though the Morgannwg system is Aled Summerhill, who made his debut for Principality Premiership side Pontypridd last Friday. Playing at full back, Summerhill scored twice against Jersey at Sardis Road but starts at outside centre tomorrow.
His match up against Llandovery's Owen Howe, goal kicker for the home side, is certainly one to watch out for. Llandovery meanwhile can welcome back Dan Brooks who plays at scrum half with outside backs Howe, Jedd Evans and Olly Smyth their main threats with ball in hand.
You can watch the college play-off match live on the S4C website tomorrow, kick-off is at 3.30pm. Full highlights are then shown on the Welsh channel tomorrow evening at 11.05pm.
Llandovery College: 15 Lloyd Rogers 14 Riven Earle 13 Owen Howe 12 Jedd Evans 11 Olly Smyth 10 Jac Wilson 9 Dan Brooks, 1 Sion Hughes 2 Daf Hughes 3 Josh Crawford 4 Rhys Verley 5 Tim Harvey 6 Alex Grey 7 Chris Williams 8 Lee Taylor.
Replacements: Harry Millidge, Jordi den Hartog, Kieran Mudd, Noah Callaghan, Joseph Hughes, James Morgan, Jack Evans, Adam Turner.
Coleg Morgannwg: 15 Tom MacAloon 14 Jack Huntley 13 Aled Summerhill 12 Gabe Davies 11 Lewis Morgan 10 Jared Evans 9 Tom Williams, 1 Leon Crump 2 Liam Belcher 3 Dillon Lewis 4 Seb Davies 5 Matthew Jeczalik 6 Jack James 7 Matthew Marley 8 Hemi Barnes.
Replacements: Ryan Spriggs, Rob Lewis, Aiden Luxton, Bradley Llewellyn, Cai Jenkins, Harri Millard, Cobi Flowers.