the update tool only suggests RAM and SSD upgrades,no blu ray drives.
This only means that Dell do not stock or provide the type of device that you require.
How can I find a better selection of BD drives that will fit my laptop as I have checked Amazon in the past and there is not much of a selection?
Honest answer is that it will be difficult as not all internal drives will be compatible with your notebook, an example of this here, a very good LG drive on the face of it but if you read the reviews you will see the following;
I purchased this and it would not fit either of the two Toshiba laptops nor my Dell laptop and I was told I had to pay the return shipping even though the description makes it appear it is an universal drive
Choosing a device that clearly states that it is compatible with your notebook is the best option IMO.