If you have never owned a crossbow, then you're on the right page, a pistol crossbow is a good starting crossbow.
Although the 40lb rifle crossbow is a good option too.
There is two main styles of pistol crossbow, a self cocking version and the standard version.
The self cocking version works by snapping the crossbow in half similar to an air rifle.
The standard verison has a pulling bar, also known as the cocking bar.
The 50lb standard version is easier than the self cocking crossbow, but obviously not as powerful.
The 80lb standard version is a little bit harder than the self cocking version, but it comes with a foot stirrup which overall makes it easier.
You can buy a foot stirrup as an optional extra for the 50lb version.
Hunting animals with a crossbow in the UK is illegal.