Welcome to the beautiful world of warbird 
Ramming the throttle is how some new pilots died in WW2. You do not ram the throttle. Ever ! Why ? Because the Merlin will develop a huge torque that you cannot control, the aircraft is going too slow for the aileron to be of any use. Not enough air pressure on the aileron foil. Move your throttle gently build your speed.
The rudder trim in itself works (at least it works on my computer 
) but it won’t solve the yaw problem at TO alone, you have move your pedals. It is not a boxing match, you don’t hit hard the pedals, you dance on them.
I strongly recommend that you start without any wind because a crosswind will complicate the matter.
A last remark : any beginner flying a warbird find it extremely frustrating. It takes a lot of virtual sweat and tears to master the beast. It is like riding an angry tiger. When you get the hang of it, it a great sensation. But it does not come easy.
Do not start by thinking that the aircraft you bought is bugged or not any good. The FI Spit is not perfect but it is good. For a flight simulator that is.