Bed bugs are a nightmare. Once they "make their appearance" you need to throw away your bed, your sheets, your rugs, pillows etc... Plus wash your clothes in very hot water. Once your bedroom (and adjacent rooms) are empty you need to fog them or call a professional service and have them do it for you. London is a city with a huge bedbug problem so it's very common to get them in hotels, hostels etc.. but my bedbug problem happened in a big city in the US.I'm a very clean person but my neighbours were incredibly filthy so my apartment got infected. What I would do (every time a had a "bed bug attack") was move to my boyfriends house for a week (while my apartment was being fogged) and wash with very hot water the clothes I was wearing. After a couple of days (living in a bed-bug free zone) my red marks and my itching would dissapear.
To the OP: If you move someplace else and the itching/red marks don't go away them its definately NOT bedbugs but something else (an allergy, scabies etc..)