I'd honestly recommend to play the Visual novel first then watch Fate Zero. Although i doubt that you can buy F/SN in english translated since the ones who worked with it, Mirror Moon or Beast's lair are just fansubbers if i remember correctly.
F/SN is my first visual novel too. It's tiring at first since the prologue is freaking long but you will soon get a hang of it. I'd also not recommend to buy F/SN blu-ray.
If anything we should hope for a Ufotable adaptation of F/SN
