How about a
Subway at £249. You get a lot of bang for your buck with a Subway. They are pretty much bomb proof.
The
Decathlon Triban 500 Flatbar is pretty good too at £260
I think that you will struggle for anything new at your £200 price point so you would definitely need second hand, but if you know what you are looking at you should be ok but no guarantee or anything second hand. If a Subway or Triban has issues, there is a guarantee to fall back on.
I've looked at Pauls Cycles for you but nothing under £299 (Giant Escape, that's a seriously good bike BTW)
What about
@biggs682 has he got anything suitable for you? He might be worth dropping a message to.
I used to cycle around Weston Super Mare a while back. I didn't die, the drivers seemed no more homicidal than anywhere else. I cycled in London too, still didn't die. Now I cycle around Norwich daily dodging busses, tractors and, at this time of year, Combine Harvesters, still haven't died. Cycling is as safe as you make it really. There are numpty drivers everywhere but they are the exception, rather than the rule.