First, you definitely don't need SPSS! The thought of any form of robust statistical analysis occuring at strategy consultancies makes me laugh!
Remember: "Source: Mckinsey/BCG Analysis" often means "numbers are mostly made up"!
The only analytical tools you will need are Excel and Alteryx. Excel is more common and practice beforehand helps. Alteryx you may never use, and, if you do, it's pretty quick/easy to learn. Tableau is useful, but not required (and also dangerous in the hands of someone who doens't understand statistics/economics)
How to Skill Up in Excel
A few good resources:
https://www.udemy.com/share/101Wde/ (Udemy is excellent. $15...basically free)
Important Tip: Don't just learn formulas etc. Test yourself! Download a free data set, ask yourself a question, and try to solve for it. Play with actual data solving real questions and building a real dashboard etc. Don't just passively take lessons :)