Wouldn't look like Discworld??? There's no official map by the author so you can shape to your imagination since every map I saw showed things slightly differently
You really do need to move the Blue Capitol to those 2 islands. You don't have to merge them into 1 island, but you should expand the one with the L1 ruin to be large enough to place a city there and make it the Blue capitol.
Otherwise Blue will just be SO far behind the the other sides in expansion and Yellow will end up owning most of the East Coast since Blue will take a long time to get there (it's 5 turns to the big island to the East & East coast of the main continent and by then Yellow will have 5-6 cities on the main land).
KGB