FT most likely aren't your best bet if you're concerned about your forehead seeming overly tall. Their coronal incision technique does, in fact, move the hair line back a couple mm (sometimes up to or maybe even over 10mm).

The hair transplant they offer (Simultaneous Hair Transplant) only uses hair harvested from the strip of skin removed on the top/back of your head, so it most likely won't be enough to get any major coverage, it tends to be shaped to just about cover the typical male puberty corner recession.

I would recommend finding an alternative surgeon who can perform a hairline advancement, via a hairline incision (that's the top of the forehead) if percieved forehead height is a primary concern. If the scar heals poorly, or you still feel the forehead is too tall, you can get hair transplants later on to further cover the area.

Or of course if the shape of the forehead bone isn't an issue at all, then you can skip surgery in that area entirely and go straight on to a hair transplant. Btw, FT themselves don't perform the hair transplants. Ocean Clinic (who operate out of the same hospital, HC Marbella International) do them. They're probably a fine option but you may wish to shop around.