Hi,
Keep trying all the 'direct' type insurance quotes from the big insurers, do the same from the 'comparison' websites, call insurance brokers and finally, call specialist insurance brokers/specialists. It's all more intense that it used to be but there are insurance companies out there willing to do more reasonable quotes/policies in terms of cost. For a long while, it used to be that going the 'broker' route would often mean a better insurance deal and it's exactly what I used to do, however when a renewal came up from them I was shocked at the price rise, I got a much lower quote elsewhere and my broker almost embarrassingly said to go with them as he just couldn't get anywhere near it! So, i've been with Admiral the last couple years. I'd also suggest looking at specialist insurers, and looking at things like a limited mileage policy if it suits you. I have a 2nd car and only use it here and there as it's a bit of a special one i've wanted for a long time, its on a limited miles policy and when I was quoted for the year, I literally fell off my chair at just how comparatively cheap it was!
Also, on this forum and similar posts before, I've mentioned there's multitudes of other criteria the insurance companies use to come to a quotation amount. The biggest one you have control over is the actual car you are considering insuring. In a nutshell, the smaller engine it is, the easier it is to get repaired from the insurance company perspective, the cheaper the insurance will be. The other big aspect with regards to this forum is getting a UK license will instantly lower your insurance premium as well, but I understand to help get that license you need to practice more and with your own car your chances would be increased, but insurance is just so expensive - catch 22 there. I'd also agree with perhaps hiring a car for perhaps 2-3 weeks and REALLY getting in as much practice as you can in conjunction with taking lessons. Perhaps look to those 'intense' drivers license courses?
The company which gave me the quote that made me fall off my chair was called 'Classicline' insurance -
http://www.classiclineinsurance.co.uk/ - although they do specialize in more bespoke insurance requirements, they can and will do more mainstream policies, however they might not be as competitive as some of the more mainstream well known insurers.
Please do look at magazines/websites like WhatCar etc, which give excellent reviews on cars and advice for cars which are 'cheap(er) to run overall including general insurance costs etc.
In general though, motor insurance costs industry wise have reduced by quite a lot in recent times. The very latest data shows the UK has the safest roads in Europe in terms of the number of accidents/fatalities & serious injury incidents over 2012.
Good luck and keep searching!
Cheers, DtM! West London & Slough UK!