Thanks to all who responded...I have now completed the job and as the 2012 on D40 air-conditioners are quite different to previous models I took some photos to post here. The filters are accessed by opening the lower glovebox and if the lids sides are squeezed in slightly it will drop down further, the cover can been seen slightly to the left, it is hinged to the bottom and held shut with clips molded into the cover top, there are no screws. If the filters are in acceptable condition, i.e. no holes, they can be cleaned and reused. It does need to be remembered that if they are to be reused they need to be cleaned properly, air conditioning filters are notorious for harbouring bacterial germs, ie Legionnaires. I used a mild solution of household bleach and warm water and scrubbed them gently with a toothbrush, I ensured they were completely dry before refitting. Note the direction of the air-flow arrows printed on the ends too.
And Happy Christmas to everyone too.