Is it possible for someone to give me some advice on why my model just does not work?

Hi all, Im trying to train a TensorFlow model to differentiate between a British one pence coin and a two pence coin.

I have 50 Photos for each at the dimension size 255 X 255, all photos are in focus and taken in natural sunlight.

Here is the training code I am using

https://pastebin.com/khjZrSgs

And here is the testing code I am using:

https://pastebin.com/1RZc35xK

I am pretty new to this and only following YouTube Tutorials, any advice would be fantastic!

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Thanks all!