Applying Numerical Values To Letters In Formula

I'm putting together an Environment Threat Assessment for work and want to automate as much of it as I can to alleviate the amount of time ppl have to spend putting values in. My main problem is I have three very important columns: Likelihood, Success Rating and Risk Rating. Likelihood and Success Rating values will be selected from the following:

VL - Very Low
L - Low
M - Medium
H - High
VH - Very High
Each of these is given a value: VL = 1, L = 2, M = 3, H = 4, VH = 5.
The Risk Rating is the result of multiplying the Likelihood and Success Rating. So a Likelihood of Medium and a Success Rating of Low will give a Risk Rating of 6. Therefore, the cells on my spreadsheet would look like this:

Likelihood Success Rating Risk Rating
M L 6
The issue is I want a couple of things to occur. Firstly I want keep the values in my Likelihood and Success Rating cells as letters (ie. VL, H, VH etc) rather than numbers, while still generating a number result in the Risk Rating cells. Secondly I'd like to be able to change the colour of the Risk Rating cell to reflect the number it gets assigned. For example Green for < 8, Amber for 9 – 14 and Red for 15 – 25. I've been trying to do this with array formulas and am basically going around in circles with no success.