It depends on what you class as soft. But there's no point in doing science based subjects if you don't like them, most people I know that have taken them just to look good have failed spectacularly.
Pretty sure Lit is a facilitated subject so universities want students to have done an A-Level of that difficulty. And in some cases Psychology can be classed as a science subject, but only some universities regard it as so, you'll have to have a look to find out. The only subject there I'd say is the most "soft" is Sociology, but that's only because I found it quite easy at GCSE - which in reality means nothing when A-Levels are completely different to GCSE.
At the end of the day, as long as you do subjects you enjoy and are related to what you want to do in the future, then it doesn't really matter. And when uni is concerned, it's pretty rare for people to not get a place as long as you get your target grades.