Unironically the most readable typeface I've ever used that comes standard on all computers is Comic Sans or a variant of it.
I've changed the typeface now, however you may have to hit refresh on your browser because I've used some pretty aggressive cache-control headers.
It's not a hugely massive change in typeface style because I really can't stand sherif when reading large chunks of text however I have also included some tweaks in the spacing which might also help.
Let me know if that has improved things or if I need a more dramatic change in typeface.
Thanks again everyone for the feedback