Will there be an option to play quick matches separate to the main game?

But... you can already do that in the multiplayer gwent that's been available for years now. Or do you mean something different?

I mean as an additional game mode in Thronebreaker.
Player vs AI with a random deck of cards for example.
I know about Gwent but wanted to know the replayability of this game.

I hope that it will have skirmish mode.

Again, the free gwent multiplayer, which has been available for over 2 years now, has this mode.

The multiplayer gwent has battles against AI. They have practice games against AI for all decks/cards.

I know that but I'd prefer skirmish in Thronebreaker with the new style as well as quick access when I want a break from the main story.

Anyways, no it doesn't.

Technically there is one but I don't think it will fit your expectations of a skirmish mode.

There is a training option when in camp mode but you are only fighting against another meve(the character you are playing as) using the exact same deck as yours.

Better than nothing I guess.
In Gwent you can only play against the Monsters AI which uses the same deck every time.
This way at least I can mix it up.
A shame they didn't add skirmish with randomly chosen pre-made decks in Thronebreaker.
I own the game but haven't played much of it yet.