How Should You Invest a Lump Sum Between 30-100K?

So, perhaps this wonderful community can help a newbie with a 2-parter here. Slowly getting my finances in order from the “Too old for FIRE” original post. Luckily the only liability above living expenses is my car payment and I plan to settle that in the next couple months when my life gets back on track. I also plan to seek better employment opportunities now I have more time for my career.

Part 1 - I’m not prying into amounts, but, how do you veterans of the FORE movement have your money structured? I.e. Checking account, Saving/Emergency Fund, Mutual, Index, Pension?
I’m just trying to get the optimum balance to create that “engine room” that will help me snowball that long term investment as well as take care of my short term needs.

Part 2 - If you had a lump sum of money (I figure the amount will make a difference) and you wanted to invest it to give your wealth a jump-start, where would you put it to optimise it’s growth.

In the UK I’ve looked at this index fund below for any lump sums I may have in the future. What do ya’ll think?

Thank you as always, Finance Family, for your thoughts and support :pray:t2: