No F on the first batch of A350. Conflicting rumors on the rest. Some saying some of the last A350 will have F. Others saying all 3 class.

Now that the 777X are ordered and all 787-10 are coming with F, I would imagine the latter more likely with just 1 (3 class) configuration on the A350. No reason to split the fleet maybe? Who knows, but not official confirmation either way. All with be 3 class until further notice from BA.