I'm not quite sure how I feel about snakes. Some of them must be nice to know. But many others are clearly not, approaching life with an over-defensive attitude that involves striking and biting, and a desire to swallow one whole.
In Great Britain - I am excluding Ireland of course - there are two snakes one might see on tramps in the countryside. The adder and the grass snake. I've come across an adder more than once. I've even managed to get some pictures, as in these August 2005 shots of two adders on the South Downs at Bignor Hill, who stuck around long enough to pose. Then, sated with my company, they both exited into the undergrowth.