Thomas is looking to make up for the disappointment of missing the final two games of Wales' triumphant Six Nations campaign - including the Grand Slam-clincher against Ireland - after breaking his thumb in the victory over France.
After seven frustrating weeks on the sidelines, the full-back is keen to play his part out on the field when Toulouse face Leicester Tigers in a European Cup semi-final at the Walkers Stadium on Sunday.
"I would desperately love to be involved in a cup final," Thomas told the Western Mail.
"These European games are absolutely huge, especially at this stage of the tournament.
"The fitness and skill levels and all-round quality are virtually the same as in Test rugby, especially as it gets nearer the final."
Whatever the result on Sunday, Thomas at least knows he has the distinction of representing the Lions in the summer to look forward to, a fact he is very proud of after joining up with his fellow tourists for the first time at the start of the week at the Vale of Glamorgan Hotel.
"Meeting up with the other players makes you realise what an honour it is to be picked for the Lions," he added.
"I'm delighted and relishing the opportunity to play with such a great squad of players.
"We know what a great challenge it will be and there will be tough times and good times on the tour.