I just threw this together, don't normally design Frigates (or anything in that tonnage range). I have better engine tech but don't have anything else above two levels of tech.
Use the CODE tags to help with the display of a design.
Fearless class Frigate 4000 tons 389 Crew 764.8 BP TCS 80 TH 240 EM 0
4000 km/s Armour 2-22 Shields 0-0 Sensors 30/30/0/0 Damage Control Rating 3 PPV 9
Annual Failure Rate: 42% IFR: 0.6% Maintenance Capacity 358 MSP Max Repair 144 MSP
Magazine 169
Military Plasma Drive (4) Power 80 Fuel Use 80% Signature 60 Armour 0 Exp 5%
Fuel Capacity 150,000 Litres Range 84.4 billion km (244 days at full power)
S8ML - 1 (1) Missile Size 8 Rate of Fire 80
S1ML - 1 (1) Missile Size 1 Rate of Fire 10
ASFC - 1 (1) Range 76.8m km Resolution 160
AMFC - 1 (1) Range 1.4m km Resolution 1
Interceptor MK1 (49) Speed: 38,600 km/s End: 0.7m Range: 1.6m km WH: 1 Size: 1 TH: 218 / 131 / 65
Hammer MK1 (15) Speed: 20,000 km/s End: 58.6m Range: 70.3m km WH: 6 Size: 8 TH: 86 / 52 / 26
ASSS - 1 (1) GPS 7680 Range 76.8m km Resolution 160
AMSS - 1 (1) GPS 144 Range 1.4m km Resolution 1
Military TH Sensor (1) Sensitivity 30 Detect Sig Strength 1000: 30m km
Military EM Sensor (1) Sensitivity 30 Detect Sig Strength 1000: 30m km
Missile to hit chances are vs targets moving at 3000 km/s, 5000 km/s and 10,000 km/s
This design is classed as a military vessel for maintenance purposes
From your design it looks like you are using maintenance storage, I would remove that and put in 2/3 Engineering Spaces. That will give you plenty of spares, higher damage control rating and a lower annual failure rate.
What is the design for your Size 6 and Size 1 missiles? If you look at my design above, the Search Sensor, Fire Control and Range of the various components are all within a few hundred thousand kms of each other.
You need an active search sensor for to complement the fire control you made for the Size 6 missile launcher.