Will I need to cover both door cards and rear side panels ?
i used 1500 x 2500 to do rear seats and 4 door cards - if the roll is 1500 wide just work out the dimensions you need to cover those areas and you will know the metres
id say 1500 x 1500 will be more than enough - you may get away with a metre by 1500 (if the material is available in that width)
i get mine from martrim and no one could beat there price per metre
there good to deal with - you can also buy a litre of contact adhesive from them, or even evo stick contact adhesive from b and q is good enough (altho more expensive) i cut mine with an inch spare around my template and simply used a kitchen knife to tuck it into the door card - my blue was classed as electric blue