How did you get the $150k figure??
This is the list for supposed economics rankings of UK unis
Sort by the graduate prospects column you will find quite a few competitive unis that would be more fun.
KCL is a fine uni, but my honest advice to you would be not to go to uni in London if you have another comparable choice outside of it. The experiences in and out of London will be very different, you will feel much more like a student at a campus/ small town uni, and you will inevitably meet a lot more people as well. This might not be too big a problem if you are extremely outgoing, but the danger with London unis is that because of the sprawl you can find that you settle into a group of friends quickly and stop making the effort to meet new people each year. That's not to say you cant have a great time, but going to uni outside of London will be a unique experience, whereas uni in London has less of that. A lot of the advantages of uni life in London you will experience doing your ACA because you will most likely be flat sharing and there is a huge amount of college study time. Plus you will be getting paid a good amount by then which is extremely helpful when it comes to living in London.
If you are really serious about your career choose LSE. But from the experience of many many people I know currently doing the ACA at big four firms, going to a good non London uni will not really hinder your chances. Accountancy is not that competitive. I mean KPMG recruit 2000 graduate a year for example (not all accountants but the large bulk will be).
Also you may be able to get a first/ high two one where similar work would get you less at LSE.
I'm not really sure why I've bothered giving this much advice to a stranger, but I hope it helps.