i would not be going on a train to london to visit a friend. why take the risk. it's not essential; the cost/benefit analysis does not compute, in my mind.
also i would keep away from anyone who has been to brighton.
i have stocks in the house i could live on for a week at least, dont most people.
also if out, using loos, remember many people do not wash hands. i never grab a door handle to exit washroom without a paper or tissue between my just-washed hand and the door.
some people's lack of basic hygiene awareness is astonishing. i remember a nurse i knew visiting me, by public transport, said she'd make tea, i had to insist i did it because it never occurred to her to wash her hands on coming into the house. she actually said they did not need it. i pointed out all the things she had been in contact with and she just looked blank, as if i was mad.
am very glad i was brought up the way i was.