When does the cam belt need changing on these engines?
As Blinky says.
And is there an easy way to check if it has been
changed or due for changing soon?
Only by previous service records. If you haven\'t got the service book, the garage that has done previous services should have a record.
Also what should be covered by a full service, and how
much should I be looking to spend?
Vauxhall will have 2 service policies for your Corsa:-
Every other year, (ie, yrs 1, 3, 5, 7, etc) just the oil and filter, then a general look around the car. This is classed as an interim service.
Inbetween each of those years (ie, yrs 2, 4, 6, etc) oil & filter, air filter, plugs, check over brakes and adjust if necessary, replace brake fluid (Sometimes they don\'t ask, and you have to request it). Other bits and pieces as well. This is classed as a major service.
I should point out that if you do high mileages, then the service interval is shorter than a year. It all depends on whichever comes sooner.