Lets assume by some miracle I manage to save up a £7000 deposit, this leaves me with some £60000 to find. At a quick google around its pretty hard to get car finance over £25000, but lets have a crack at it and try autotrader. They'll only let me borrow £50k over 60 months which gives me monthly payments of £958.
My monthly take home is £1800, so that leaves me with £852 to play with, my rent is £450 and my council tax is £101, so now we're down to £301 and I haven't paid for my utilities yet.
So an electric car in my lifetime (or at least one with a useful range like the Teslas) is a distant dream. At least until the Model 3.