The route's OK, but you have to have the LGW-GIB coupon on the ticket. Since you aren't at the 20 segment limit this isn't an issue.

Obviously the route is not optimized for miles.

The hold baggage on all xONEx tickets is the piece system, so 2*32kg checked bags. On the other hand for cabin baggage you'll be subject to whatever the limit is for each individual airline on that sector in the class you are flying. This could be as low as 7kg and 45" total dimensions.