If you have a Logitech max key keyboard there is no windows key, but:
you can use the start plus the . keys together.
Note you cannot use the . key on the numeric section, only the alphabet section
It then brings up the screen Allanswood has uploaded, but:
after you click on the omega button you will need to click on the infinity icon, third from the right on the bottom row to see the fractions.
On my system that selection is stored so next time you want to use a fraction it comes up automatically.
Assuming you're posting to Stampboards from a keyboard with a numeric tablet, it's much simpler to remember the commonly used shortcuts:
Alt with 0189 inputs a ½
Alt with 0163 inputs a £
Use your mouse to click on the start key, select windows accessories, and then select the character map. The £ symbol is to the right of the 5th row and the common fractions to the left of the 7th row