As far as " Is This Really The End Of My Omega?"
you need to consider a few things
has the car got any other issues ? e.g rust that will need resolving to pass MOT
if there is a bad infestation of tinworm or other expensive jobs (other than the engine) it may be the end.
If the rest of the car is in good shape ,no structural rust then it is probably worth he time/cost to resolve the engine issue.
finding another car (let alone a good 15 year + omega ) without issues (people sell cars for a reason) is not easy
"better the devil you know" , unless that devil is rotten as a pear and falling apart ,needs major repair ££££
Finding someone local that knows omega engines that could look for you would be good
the advice you get on this site will be very helpful too
(because on this site people have owned omegas and gone through it all. unlike the AA man who plugs a scanner in for the answer ,or a garage that may never have done much on an omega engine wise (other than change the oil )
Jm2pw