At 23 you are thinking of investments and are also fairly clear on what you want, which is indeed commendable.
As you have correctly decided (with your boundary conditions) bonds, bank fixed deposits and debt based MFs should be your prefered investment vehicles.
One suggestion would be debt based mutual funds with a portfolio of a mix of medium to long term corporate/sovereign debt (good rating, like AAA etc), with no lock in period, if you can keep the money invested for 4-5 years.
For anything shorter select a debt oriented MF with a mix of short to medium term corporate/sovereign debt, again with no lock in period.
I mention no lock in period because going ahead you will have options to liquidate the low risk investment and go for slightly higher risk whenever you choose.
This edit is relation to your comment. (this should be a comment but is getting a bit big)
I agree with you to an extent on the credit rating part, however, that is my personal opinion only. I have personally seen a debt fund investment go down by 10% on account of a corporate debt write down. However, if you look at some good fund houses and analyze their 1month, 6 month, 1 year, 3 year comparative return for some debt funds and also compare them with the category average you will get a fair idea of its performance. In addition, if you also look at the fund manager's performance on other funds you will know the stability of the fund. Another option is to look at sovereign/gilt oriented funds, govt. debt is slightly more stable but returns slightly less.
However, with your age and timeframe available for investment, I think you could take the slightly higher risk of corporate bond oriented MFs.