Help required for this SMPS Battery Charger

[xyz9915]

Hi! The attached file is a schematic of 50KHz SMPS power supply which uses 325 VDC (after rectification of Mains 240 V). The required current is approx 15 Amperes, the feedback control circuitry is to keep the design stable. Please point out if any further modification is required.
Note: mains (AC) isolation is not required & the charging ON/OFF control circuit will be made with operational amplifier. At this time my focus is in the power section of SMPS, so Please point out if any further modification is required.

[xyz9915]

Following modification in the circuit is made with Opto feedback control circuitry to keep the design stable. Opto is used for isolation and simple current regulation, the question is that the 0.1 ohms/10W resistor are sufficient to drive the transistor ( about 0.7v) or its value may be increased? Please point out if any further modification is required.