The usual problems with the Omega.
Change the cam belt at 30k-40k, costs approx £350. Get it done by a dealer. There would be one hell of a bill if this went wrong...
New exhaust at 45k, brought at Kwik-Fit for £240.
New front wishbones, both sides, brought from www.autovaux.co.uk (pattern part, but made by the company Vauxhall use..), £125..., then fitting (www.mrclutch.com), £96 labour.
The other important thing to do with this car is to change the oil every 10k, or the breather pipes on the rockers get blocked and the pressure builds up and blows the rocker cover gaskets. 4 hours labour and can cost a lot of money in parts if you need to buy new rockers (£110 per side...). This also puts oil on the plug leads, and again costs a lot to fix.