I need to trim abit more of my forks however I was also considering trimming my frame seat tube by about 1/2-2/3inch.

Where is best etc?

Just any old full size one from wherever’s cheapest and handiest. Make sure the guide rolloer can fit fully on the fork or you could end up cutting a thread! Or use an old stem and a hacksaw, might be better if you’re only cutting off a few mm.

I was also considering trimming my frame seat tube by about 1/2-2/3inch

That doesn’t sound wise. What’s getting rid of that 1/2=2/3 going to do for you?