Another thing to note is that the income distribution in London seems bimodal. And so if you are earning a good amount, you may still find it a bad idea to assume similar good income in the future and therefore not want to get into a huge mortgage.

So yes, you may technically be able to afford a decent house, but in practice find it a very bad idea to do so. E.g. imagine if the OP got herself into a massive mortgage - she would feel even more trapped than she is now.