If you don't have the money, you can also just train yourself sufficiently to get that confidence you are talking about.
...I'm not saying a course wouldn't have benefits, but if you just want confidence at 700 yrds with a .308, I mean, this is exactly what I did. I have a 20" .308 in an AR-10 platform. Chances are you have a better setup than me. Yet, even at my first outing, I felt like I couldn't miss an 8" plate at 620 yrds; there was almost no excitement after a while because I would hit the target every time.
I'm no professional, but here's my thoughts:
1) You first need a gun, a cartridge, and a scope you can have confidence in. If you reload, great! I don't, so I tried many (29) different .308 cartridges in my gun. After a lot of testing, I happened to find that the overall best cartridge (an equation I made of most accurate, lowest deviation of fps, and flattest trajectory), was Hornady Superformance A-max in 168 gr. You'll want to find a cartridge for hunting that has the most consistent performance.
As far as a scope goes, the mechanical performance (tracking a repeatability) is the most important attribute. There are ways you can determine if your tracking is spot on. (see this article for ideas:
https://precisionrifleblog.com/2014/08/13/tactical-scopes-mechanical-performance-part-1/)
2) You need to calculate your point of aim. The easiest way is to get yourself a good ballistic calculator, and all that that entails.
You need to know your cartridges muzzle feet per second speed. Borrow or buy a chronograph. If you have the money, get a Magnetospeed or LabRadar. (I used a Caldwell chronograph). You also need to know the atmospherics you're operating in. Kestrels are the best, but again, I didn't have the money. So I borrowed my home's Acurite weather station (which tells me barometric pressure, humitidy, and temp). I now have a watch that does this (minus the humidity). These numbers are important for your ballistic calculator.
There are a lot of good ballistic calculators; some come on the Kestrel. Again, me being poor, I just bought one for my phone (Strelock Pro) and it works great. I like Strelock because it shows an image of your scope's reticle (it has hundreds to choose from) and shows the point of aim and/or clicks on your turret to make. Probably the one with the best reputation, however, is Applied Ballistics. Here are a couple articles on ballistic calculators:
https://precisionrifleblog.com/2019/05/22/ballistic-app/
and
https://www.snipercountry.com/best-ballistic-calculator-app/
You also need to determine the distance to your target. A laser rangefinder is best ... but again, me being cheap, yet having a first focal plane reticle in my scope, I figured out how to range-find using just my scope.
Now I just plug in the data into my phone, shoot, and I'm golden. It's too easy!