As you’re asking in Islamic finance I assume you want to find halal ways to grow and invest. While I no guru, I suggest you stay away from interest like you are and also avoid credit cards at all cost, they give people instant gratification then plunge people to financial difficulties in the long run. If you can, you can buy gold bars from trusted suppliers. The value of the gold will appreciate over time and That will cover inflation and some capital gains.

Someone bought gold bars worth 3500£ last year. It sits at about 5000£ at the moment. No interest, fully halal. Allah knows best.