Honestly, not to "shame" the op or anything, everyone is allowed to exercise whatever level of caution they deem necessary.
I presume based on the OP location and the forum this is in that they live in the UK. MOST of this proposed travel is within the region. So unless you've been holed up in the house this whole time, there's no more risk being out and about in Edinburgh or London than there is in going to the grocery store in Plymouth. Unless you really believe that just the sheer number of people in those cities is threatening. More towards the germ fraps known as aircrafts...I mean you (and WE) always run this risk. Being on a bus carriers the same risk, so does being anywhere that has lots of people especially in concentrated areas. Again, if you feel the need to exercise an abundance of caution, don't go, but remember your daily life when fretting about it.
I've seen plenty of masks lately, I work at an airport and I've been doing my usual non-refundable travel. I haven't worn one, but I bought some and I might use them when I go to Thailand next month, JUST in case. But honestly, I'll probably pack them and then not use them. I was on a business class flight between San Francisco and Lisbon and there was a guy wearing not only a mask, but also wearing latex gloves.
I think the biggest thing here, is look at yourself and determine if you're at risk. Are you travelling to China? No, that would be my other advice, is to not go to China right now. If you're at heightened risk to pneumonia or flu every year due to your age, or other auto-immune deficiencies then I would absolutely be avoiding any travel outside the region.
Even then though, it would be up to you to decide how close you'd get to the epicenter before you thought it was too risky. Is it possible an infected person is walking the streets of Glasgow or Amsterdam? Sure it is, are you gonna come in contact with them? Who knows.
Personally I'm not in an at risk group and I'm not terribly worried about it. I cancelled a couple nights I was supposed to spend in China and swapped those for just 2 extra days in Thailand, but that's really the only changes I've made. My bigger concern is buying a ticket, connecting in China (because it's cheap) then being denied entry or quarantined whenever I go somewhere and they see it's in my passport.