The former Strathendrick player, who also played for Glasgow Hawks on their successful tour to South Africa last summer, said: "I couldn't have picked a more exciting place or a better weekend to make my first starting appearance.
"With thousands of Scotland supporters in Cardiff for the Six Nations game, there is bound to be plenty of backing for us and that should give us a bit of additional confidence.
"Their presence will turn the occasion into a really big event and I am determined to take my chance. The ball is in my court so to speak."
Glasgow backs coach Sean Lineen has no doubts Gregor will fit the bill. He said: "Colin has blended in very well at training and has struck up a slick partnership with Graeme Beveridge.
"It is a massive opportunity for him to state his case and I believe he will do a sound job."