Blimey Terry
which car ? the 160k+ onen or the 120k ?
assume either way it has P155 5w30
rather tan the TC 10w40 semi I suggested
I did an oil change on then wife's new astra H 1.6 recently and noted the oil filter for z16 xep is not the standard spin on that fits most vauxhall of the era but a bigger spin ion filter, what did you fit ?
oil pressure switches are common to leak or bring the low pressure light on true enough BUT.....
an oil and correct filter change (to 10w40, not P155) may be a good idea
and there is that possibility that you have blocked the oil pick up with crap, washed out with P155 oil
also you need to confirm it is oil pressure and not oil level warning light.
as for recovery back , being london , i expect it won't be cheap
also also
being london , i expect the car sits in traffic for hours and gets hot ,which thins the oil anyway , plus if the thermostat is not opening or any problem with the fans not working (you need to check ) will thin the oil to bring light on .
there is no temperature gauge on the dash ,you have to view the temp via the radio/display or bluetooth elm327 (about £5 delivered) or similar .
anyone local to the car that could do an oil and filter change Terry ?