Adrian
That's a shame, but give my best to your mum and enjoy dinner.
Like me, they're not big drinkers, but you'll never go wrong with a good red wine, and dad's been known to have the occasional whiskey. I do know you, and I'm sure that whether you bring anything or not, they'll enjoy having you there.
Don't know, actually. Not sure whether Nanna and granddad will be there, but they're somewhere else, you'll be fairly safe and just have to answer the standard things about interests and hobbies and your parents, etc. If Nanna's there... Let's just say that subtlety's a virtue she's never practiced, and she's been muttering about it being too long since she's been at a wedding. Nanna likes a good glass of port, so maybe she can be distracted?