First I'd ask - how much data do you wish to store ?
Remember each DVD can store around 4.5 GB but if you groups photos and music into 4 GB chunks, it will give you an idea of how many DVDs you might need.
Once you know how many you can see whether it is worth seeking some online supplier for DVDs in bulk (to save cash) as packs of 10 in supermarkets or PC World would work out far more costly, in my view.
Next, you need to know what your laptop's drive is suitable for using (the DVD+R or DVD-R difference) and then test out the drive... Poundland or a supermarket might do a pack of 4 DVDs for a quid or three, so you can play experiment without having spend 25 quid on 100 of the wrong DVDs...
I (or others) can assist, but finding out the specification of your exact model of laptop, and/or checking what the make and model of the drive, will help.
Right, that's a start... Might be worth searching for past threads about "reducing duplicates" because having two or more copies of the same photo seems a regular problem...