You've put a few questions out, so:
Most suited for woodsball - actually any paintball gun
There is no such thing as a woodsball gun, there are ones that some people call woodsball guns but that's only them association the gun with the woods
They all fire paintballs at up to the maximum velocity the site allows.
This is highly subjective regarding gun choice. The only reliable way to choose is to look around, go to walkons etc, look at other peoples guns, ask to handle them, possibly get to shoot them
Pistols - good, cheap, .68" and mag fed don't all go together
The kings of this are the tiberius and Tpx pistols
Opinion sways either way, but the Tpx is probably the current winner
The disadvantage is that the 12gram is in the gun. If you use it for more than a few shots then you have to change the 12 gram when it runs out which could be an inconvenient time. But convert to compressed air for more use then just keep on reloading magazines
With the Tpx the co2 is in the magazine and you can swap to another magazine with full co2. Carry as many magazines as you like and also reload with paint twice to get full use of the 12 gram. But that means you commit to using as many 12 grams as magazines carried, even if you do not fire single shot
Other pistol choices are the BT sa17, delta 68, war sensor / armotech. These are older designs and are cut down versions of normal paintball guns (EG spyder clones) thus they are still chunky
There are a few other obscure and old school pistol options if you find them
And if you divert from .68" there are other calibre pistols such as .43" or .50"
For pumps, don't necessarily stick to stock class unless you do have a preference or stock class games available.
There are a good number of pump players in the UK but not so many to make stock class events very viable, there are limited paint or pump games about and quite often something as a side activity to events
You can get anything from old site guns, to bling pumps.
Some models come ready in the box to switch between hopper, spring feed, gravity stick feed etc
There is also the option to convert some guns to pump, particularly autocockers, but the pump kit usually needs to be self imported