Mosfet needs to switch 100V - 350V and up to 7A of current
I think you may need to have a good think about your choice of MOSFET: -
At 7 amps, it will drop about 1.7 volts between drain and source and dissipate nearly 12 watts of heat. This will cause it to warm (even on a heatsink) and, as it warms, the volt-drop increases. Here's what the volt drop might be around 150°C: -
At this high limit of temperature, the device will be dissipating about 29 watts so, you definitely need a substantial heatsink if you are to avoid it warming up to it's limiting temperature.
And, bear in mind that the junction temperature will be significantly higher than the case temperature and it is the junction temperature limit of 150°C that is to be avoided. That fact and the thermal resistance from junction to case imply to me that you need quite a sizable heatsink.
For instance, if we draw a line between the 12 watt power dissipated at 25°C and the 29 watts at 150°C then we might expect it to have to dissipate 20 watts at around a case temperature of 90°C.
So, given that the local ambient temperature around the heatsink may rise up to around 50°C, the heatsink itself will have to have a thermal resistance that is better than (90 - 50)/20 °C per watt. That equals 2 °C/watt.
So I was wondering do I need a gate driver circuit for low frequency
task that I have
It's unlikely that you will need one but, that isn't your big problem as far as I can tell.