If I have a disc copy of Lego Worlds for xbox one, and i have an xbox series X, would i be...

Yes. You would just put the disc in like you would on a One and play it like normal.

see i had bought the lego hobbit video-game on disc last week but when i asked at the cash desk of where i was going to buy it i asked if the game would work on xbox series x and i was told no so i never got it in the end so the disc version of lego the hobbit will work on xbox series x correct ?

It is compatible with a Series X. It is not compatible with the One or a Series S since it doesn't have a disc drive.

According to my Xbox Series X|S, the disc is “incompatible”, and I can only play a compatible version of it if I pay $62.99 for a new copy WITH EA Play.

I think they have given me the wrong disc version

On the disc is says "Xbox One - Xbox Series X"

I believe this is the Xbox one version that is compatible on Series X

Because I'm sure the Xbox Series X disc should say "Xbox Series X" and not Xbox One

I have contacted the seller and awaiting a response but thank you for your help

The Xbox series X will not read the MW2 disc, I have returned it and tried 3 separate copies of the MW2 disc, the console will play other games/discs and read dvds/blue rays as well. But will not read any MW2 disc I insert into the console. The disc will read on my Xbox one. I installed it there and network transferred all the data to the series X and upgraded all the data that was transferred but the console refuses to read the MW2 disc.