I for one don't have much faith in notional weights. For example, the last time I was at the notional weight for an adult male, I was 14! And how often these days is cabin baggage less than 3kg per person! One aircraft I used to fly had Weight and Balance Computers which calculated the aircraft's mass and C of G from the pressure in the oleos. WABC mass was always greater than loadsheet mass. If you saw a 747 full of average size Americans who had to strain to get their '3kg baggage' in the overhead locker, you could understand why the WABC mass was once 8% greater than loadsheet!
The A320 series allows you to access the FAC computed mass. Go to MCDU menu > AIDS > Parameters > ALPHA Call Up and the FAC computed masses will be displayed. There are restrictions and I think .1 degree of pitch equates to 3 tonnes, but in my experience they are more accurate that the loadsheet figures. I change the Vapp to allow for this allowing 1 knt per tonne. This isn't necessary on the 320s I fly, but the 321s are always heavier that loadsheet by about 3 tonnes. On the approach, I check the 'gap' between VLS and Vapp and make it a minimum of 5 knts.
Also, if the aircraft is struggling to get to height, sometimes putting the FAC computed Mass into the MCDU on the Fuel Prediction page will give you more accurate Optimum and Rec Max Alts. On more than one occaision, the new weight has shown we couldn't get to our planned cruising Alt.