I'm back in Blighty now and, as I said, will update the thread with my experience. I went the court route as explained in previous post. It went much according to plan and without hitch, hassle or surprise. It involved waiting here there and everywhere all day from morning till flight but that was expected. The immigration officials were courteous-friendly almost like tour guides getting people to follow them. They are dressed plain clothes jeans Tshiirt and no handcuffs. Total cost of the court route "package deal" was 15K including fine, transports. So its 5k less than the 20k airport routed with a day of waiting around on the negative side but on the positive the certainty of getting out on the desired date without risk or airport immigration causing problems.
In retrospect the airport 20k may be good for those with relative short overstay but given the length of my overstay and the seemingly "get tough" on overstay climate I prefer the certainity and plannability of the court route to putting faith in airport immigration.
Once again, many thanks to toddaniels for putting me in touch with his contact, who was friendly, reliable and had the connections.
@tod - pm me your email address pls. Bloody yahoo won't let me connect to my email because I'm connecting from a different location. It wants to send a sms to my mobile which is in Thailand.