Essentially you don't strictly require any monitoring unless you get unwell but:
4/54 == 4 weeks post starting treatment
FBC = Full Blood Count = CBC = Complete Blood Count
Cr&E = Creatinine & Electrolytes = UEC = Urea Electrolytes Creatinine
LFTs = Liver Function Tests like Bilirubin, ALP, AST, GGT, Albumin
Hep C Viral Load = Quantitative HCV RNA
The 4 week test typically shows (80%) viral load zero and proves the meds are valid and working.
If you want an early proof your AST will fall rapidly back to normal
Once viral load is zero there is really not a lot of need for further monitoring (unless on Ribavirin)
The 12 weeks versus 24 weeks length decision is based on Fibrosis. If you have cirrhosis (F4, > 14 kPa, Hepascore > 0.5) then you need 24 weeks.
Next test after viral load zero can be SVR4 or SVR12 - Viral load 4 or 12 weeks post finishing treatment, and a VL=0 at 4 weeks = 96% chance of cure, and at 12 weeks 99% chance.