HC1811
What you want is to be early semi-retired, as opposed to early retired.
Figure out how to make 5k a year doing something pleasant, or something simple you can do in a few hours a week or a day a week.
Then withdraw from your financial savings at 4% or 4.5% just like the rulebook says.
If you do that, you'll find your numbers work out.
btw, are you talking pounds or dollars? If dollars I am suspicious of the 17k figure.
When I calculate an annual budget, I try to be sure to include some sort of accrual, or amortization for the wear and tear on a car (to fund an account to replace it one of these days), and the predictable maintenance (in my case, exterior painting every 7 years) on your house. If you do that, you might find your 17k is closer to 20k. Good thing you have national health insurance covering your medical, too!
So you might actually need to earn 8k a year to be completely sound. But a bright 31 year old should be able to do that. Your real estate expertise sounds like you're on the ball -- maybe you can rehab another property, or manage somebody's property to earn a bit each year.
Making your money 'work harder' sounds like a short term solution. You'll inevitably start ignoring inflation, or taking on more risk than is prudent or something like that. The SWR studies all converge on 4% long term for a reason. Bigger numbers just don't work out, at least not initially. Years from now, after the Boom of the 2010s, you'll be able to look back and think, ahh... yes... but for now you've got to assume the 2010s will be just like every other decade and stick with normal long term projections.
To take out your 4% safely over time, you should have the funds in a broadly diversified, low fee, low volatility investments. ER in early 30s means you have to pay particular attention to the things that can mess you up over the long run. That, or plan to start a second career at some point.
Good luck with it!