Firstly, stop replacing dodgy sensors with second hand crap from breakers...
Secondly, apart from the head gasket, which I presume you knew about before buying the car, nothing on your list is beyond normal items that every cheaply bought Omega would need replacing in the first couple of months of ownership/for the first MoT...
Love your Omega right, and it will reward you like a friendly retriever
Thanks Al ... I have been told

The only reason I was wanting a second hand sensor was to try and get me by until my next lot of available funds arrive

Lesson learned (the hard way I must say)!
I do love my Omega to bits, I really do. But sometimes it can be a little bit testing when everything breaks in the same week! I only want to use GM parts after my experience with the pattern parts available ... that is unless it's something really special, like a set of wheels or something along those lines! This in itself makes things a little more costly and I do feel the need for an ABS membership maybe for easy access to trade club prices

And hey you guys help to give me the motivation to keep on plodding along, this is very needed sometimes

I unfortunately seem to have caught some kind of illness from the Oof site though

I'm considering the purchase of a late (52 reg) GLS 2.2 16v Manual, it looks in fairly good order and is full of base spec charm in a way no other car than a Vx can offer ... It would be as a second car so as I can run the auto for 6 months and then the manual for 6 months throughout the year, this would give both cars a good spell of dry stored repair