Using an IFA but having doubts

I’m semi retired and I’m looking to invest about £300k for about 5 years. I know next to nothing about investing and feel too nervous/under confident to do it myself- so decided to use an IFS. They recently recommended that 5 years is too short a time, and I was better off keeping it in cash (savings accounts). I guess this is the age old question - where best to put your money. Thoughts?