Currently I am PhD student in Switzerland, recently I got Postdoc position for four years in King college London with salary around 30K. I am a bit worried about living cost in London. I did some search and found out that rent is very expensive in London, more higher than Switzerland, however the salary is high in Switzerland and even as PhD student you have a comfortable life. Since I am not swiss and Switzerland has difficult rule for immigration, I made decision to leave Switzerland for my future carrier. I am going to move with my boyfriend and he is mechanic. I am wondering if both of us can rely on my postdoc salary until my boyfriend find a job. Is will be easy for my boy friend to find a job as mechanic in London? I would be thankful if you could give me some ideas about this situation.
Information on the median income in the UK is available for 2013-2014. The data are for personal income and not household income. For the inner boroughs of London, an income of £30,000 would put you above the median income in Greenwich, Hackney, Islington, Lambeth, Lewisham, Southwark, Tower Hamlets and below in Camden, Hammersmith, Kensington and Chelsea, Wandsworth, Westminster.
As for your boyfriend finding a job, this will largely depend on his citizenship (or at least on his right to work) and soon on the Brexit. Unemployment data are also available. Unemployment in London is about 6%, so it is not trivial to find a job.
You should also be aware that the UCU salaries are publicly available. In general a post doc would be expected to start at point 23 (£23,256 per year) with a London allowance of £2,725, so 30K is on the high side of things.