Been down bottom of garden today and noticed some holes in ground, Spotted 3 rats in garden last eve on Bird table

We live on outskirts of New Forest and right opposite farming fields so i know there is alot of wildlife about. ie seen foxes, owls, mice etc but not had this in Garden before.
I have just checked on Net and the nice habitat for wild rats in country does incl Gardens with ponds, gardens where birds are fed, Garden with decking for nice nest making. ...... ooops we have all three!!

and i have seen dropping in garden as well and been told they pee everywhere.
Question is - Is it safe outside for the lads and for us? Can any of us pick up any diseases from say sitting on benches Rats have peed on etc?
We did have a few small rats caught and brought in last year by the lads but the ones i saw yest were huge!!
