You won't be given that by the tower you just get a single value or the 3 values.
Your getting confused between preflight planning and inflight.
Metar RVR does matter in planning for say LVO on departure and you need a take off alternate or not and same for TO alternate selection.
It would help if you tell us your experience level and if this is you trying to get your head round it for exams or for real life operations.
Oh and as wiggy states above... there is a difference between what type of flying you are doing. Regional stuff with flight times between 40mins and 1.5 hours we will factor in the current metar but there is no legal requirement to do so. IT would then be a commercial decision to stick extra fuel on and go and hold till it clears up or sit on the ground and wait until the sun comes up.