I have now been studying/learning German for 5 years now. Unfortunately my conversational skills are relatively poor, I have found that with my time at school, grammar and vocabulary has been prioritised for the exam specification rather than communicating and speaking with others. A spontaneous, natural conversation seems challenging due to this style of teaching. As I am continuing to study German further, what is the best way to progress my conversational skills and become more natural in speaking without immersing myself in a native speaking country.
This is a general answer, not limited to German. To really become fluent in a language you need to maximise your exposure to it.
Read other stuff than textbook German. That can be comics, books, German forums. I would not advise reading poems or newspapers, as the style is often different to conversational German.
Just listen to Germans talking. This can be German movies or series with the advantage of adding German subtitles to make it easier to understand. Watch some German streamers play your favorite game on twitch or YouTube, listen to a German podcast.
Find tandem partners
There are a lot of websites dedicated to connecting people that want to learn each other's language. I myself found some Finnish people that wanted to learn German. This way you pick up a lot of the spoken language/slang while simultaneously keeping it at a rather simple level where you both can still understand each other.
Find Germans in your area
Maybe there is a Facebook group or something where Germans living close to your area are connecting with themselves. Tell them you want to learn/practice language. You can start hanging out together. Again, this also worked for me really well.
Go to Germany
Why not spend some days in Germany? Do some sightseeing and strike up casual conversation with your waiter, the taxi driver or just some random folks in a bar. Ask people for directions and mention that you're learning the language. Most people will show some interest and engage in small conversation. If you've found some tandem friends before you can meet them. Of course make sure you're not bothering anyone. Especially during rush hour, waiters won't be prone to be very talkative.
Edit: A very strong point I want to remark: don't be afraid to make mistakes. German is a very difficult language and I don't want to crush your hopes but you're probably not gonna master it perfectly. That being said: Germans will still understand you effortlessly, if you use wrong articles/declensions. Even wrong conjugations like mixing up strong/weak verbs etc. won't hinder you in getting your point across. It might be tedious at first but keep on going and you'll improve in no time
When you have no German speaking people around to actually speak with, it might be a valid second-best option to read (and later probably even start to write) in German language forums.
For example you could start right here with German Stackexchange and specifically look for questions asked (and answered) in German. You should not limit your reading on this site, though; look for a German site about a topic that you are interested in so you can start participating in the discussions once you've got a feeling for the language on conversational level.
It seems to be a widespread occurrence that teaching foreign languages in school does not prepare you for conducting a conversation in that language. I had English as my first foreign language in school for 9 years (grades 5 to 13), had always good marks and chose English as one of my 4 subjects for the A-level exam (Abitur in Germany) - yet I was absolutely not fit to simply chat in English. I only acquired that skill later after
1) I started reading more and more texts in English (mostly on the internet, which had not been available during my school time in the 70s and 80s)
2) Having to talk to people while on vacation in English speaking countries,
even though my skill at using the correct grammar was definitely better at the time I took my exam and has declined to some degree since then.
Probably the best thing you could do is to watch movies/series in German. My cousins (Who are native English) have done that for about a decade and their German is almost flawless.
Reading books is also a good idea, although you need to be careful what books you read. You shouldn't read anything too old, it's very different from normal, modern, conversational German. German movies are honestly (Most of the time at least) pretty bad, and you might not want to buy German imports.
So, because listening is very important in learning a language, I would advice you to listen to podcasts/audiobooks. There was a German call in show called "Domian", it ran for over about 20 years, I think, a lot of it is on youtube for free.
There are also websites where you can talk to people who are native German speakers who want to learn English, this is probably the best way to learn a language if you can't move to a country where that language is spoken.