You're now at a point where you're doing research and optimizing for better decisions. That's great!
The easiest way to approach debt and investing is to generalize that they are "all the same" and just look at the interest rate, and then start with the highest and go from there. As far as investments go, be realistic about how long you will let the investments go, and then use the average return over that length of time as your comparable rate.
Saving up for a house in a few years generally means you won't have a long enough timeline to reliably make money off high risk, high reward investments. You'll want to be very conservative, and even stick to cash as you approach the house shopping season.
Saving for retirement is typically a much longer timeline, so we generally use averages like "7% real return" (i.e. 10% annual return on investments minus 3% average inflation.) For simplicity, and to start off conservatively, I'll suggest you assume 5%, and compare that to your debts.
From there, you can see that paying off the 6.8% is your first priority. Do that, all of that, before anything else. Get that paid down and get a guaranteed savings of all that interest.
Once that is done, depending on your goals, you might want to start saving and/or investing.
As far as property goes - that's a whole different discussion. It can vary wildly between regions whether it makes sense to buy or continue renting, and it also varies wildly depending on your own financial situation, how close you might live to a job, how long you can be sure to stay in one place before having to move, and so on. In other words, until you fully understand how to compare those two options down to some nitty gritty details, it's probably safer to continue renting, and if you start to build up savings, you might be able to designate that for long-term investments, and prioritize it over your lower interest debts.