Why are you trying to remove the transverse screw???? It isn't necessary to take it out to remove the fore end. Have you removed the butt bolt?
That screw is in place for a good reason. If for some reason you feel you must remove it, you will need a slotted screw driver for some of them and something to hold the screw head on the other end.
You need to go online and look at the sites that show you with pictures how to disassemble a No4 MKII rifle properly