To cancel or not to cancel ?

[peewakio]

OK so we're fully booked for next October and the savings going well. We're staying a CSR for the full two weeks with DDP with about £1k worth of other things such as Discovery Cove, HHN, KSC, Universal to pay for as well. We should be in the position to pay off the holiday in full by December at the latest.
That's all well and good until my youngest son now informs us that he's getting hitched next May.
Now I don't earn big bucks and I've been in serious debt before and promised myself 'never ever again'.
So as the father of the groom I really would like to contribute to the wedding in some fashion although to what extent I'm not really too sure what's expected. I'm divorced from my sons mother and I've no idea what she's planning to contribute if anything, or really care for that matter.
The one thing I do know is that I won't be flashing the credit/debit card around for either the holiday or the wedding.
Just wondered what's the norm with regards to a grooms fathers responsibilities these days as I really don't want to cancel the holiday or in fact be a skinflint in any way as it's not every day your kids get married, but I do envisage having to fork out a few grand for the wedding. Any thoughts dibbers?