Thanks for all the feedback. Right then, I'll get all the parts including a water pump in good time ready to do the job at 40,000. I already have the DVD and very good it is too. Thoroughly recommended.
My 200 miles for £24.50 was with numerous short town journeys, if that is below average mpg maybe I need to check the system over. But that's 20.4 mpg @ the 55p/litre for gas that I paid. If I were to go on a single 200 mile journey I'm sure it would be a lot better.
The car was cheap, although not as good a bargain as some that I've read about oon here or seen on eBay. It had a fubared ABS ECU, blowing secondary air injection pipe (thought originally to be manifold), no tax or MOT. The multi-ram wasn't working because of a broken solenoid (oh, didn't fix that 'til Friday, maybe that's why consumption is up?). The previous owner was faced with yet more big garage bills and just decided that he'd had enough.
On the other hand it already had lots of work done recently before I won the car such as new discs all round, new exhaust, cam covers, etc. So I am more than happy with how it's turned out (of course I did all the all the current work myself, with guidance from this forum for which I am bery grateful). It is also in my favourite colour -the metallic green -with light grey/magnolia? leather. It also has the (optional?) sat nav, which works. And yes, it had the multipoint LPG system already installed, which is why I wanted the car. On top of that -get this -the vendor delivered it to me for free, from 90 miles way! How is that for a good eBayer!
I have to say that much as I love my 60,000 mile Monza GSE, I'm also falling in love with this Omega. Both being 3-litres, they complement each other very well.