Because I don't. 
I have approx 20k. That i don't need for 4-5 years.
I have another 25k that I will need for a tax bill next year.
I have no clue how investments work. Wether to look at ISA or investment or investment ISA. Or just leave it in the bank.
Can anyone point me in the right direction of some good information?
Investments for dummies, if you will. 
Many thanks