i have complete pack black gate , serpant isle ..etc i would just like to know which game i start first and does your character carry over to the other parts ...etc black gate , serpantt isle.

Start with Black Gate.

I don't know whether the character from Black Gate can be transferred straight to Serpent Isle.

They can not

They can not, but in Serpent Isle you start with a lot of stuff you can (should) collect in TBG.

That said, Serpent Isle IS part 2 for a reason: the story of Ultima 7 is picked up and continued

Enjoy!

Since The Black Gate is called Ultima 7 Part 1....I'd suggest starting with that one.

Like others said, the order is as follows:

The Black Gate (main game)
Isle of the Avatar (expansion, to be started at any point during BG)
Serpent Isle (main game and sequel to BG)
The Silver Seed (expansion, to be started at any point during SI)

If you're going to play only one of those, I recommend The Black Gate. Serpent Isle requires more backstory, and appears to be unifinished, judging by the lack of content near end-game.

Interestingly enough, the timeline for Ultima Underworld 2 actually occurs in between Ultima 7: The Black Gate and Ultima 7 part 2: Serpent Isle. It doesn't add much to the story, but does explain where the blackrock serpent appeared from in Serpent Isle.

Definitively start with BG for an exciting open world experience and continue the story in the much more focussed - in a good way imho - SI. I love them both for their specific nature. Two of the best in my book.
I never understood why they had to connect the story of UU2 to Ultima 7, it always seemed extremely artifical and illogical to me. Spoony explains my feelings very well in his review in the Ultima Retrospective.

Dude lol this is the kind of lore and deep meaningful discussion I'm here for. Then I saw your avatar and lost it lmaoooo I literally pointed at my screen. bong, bong, bong, bong... XD