Son And I Wondered...

[ferlew]

Mr F often uses the saying... "Well, I'll go to sea in a bucket" anyone any clues what this really means.

(We realise it means unexpected)

[heathfield]

Maybe your mum's more polite form of the saying "Go to hell in a bucket", which means where something's wrong, it'll only get worse

[bookbinder]

It's what's known as an expression of surprise. Here's a few examples:
http://dictionary.cambridge.org/dictionary/british/well-i-never-did
http://dictionary.cambridge.org/topics/using-the-mind/expressions-of-surprise/
It corresponds with:
I am really surprised by (at) that!
You don't say!
Goodnes me!
Well, fancy that!
Well, I'll go to the foot of our stairs!
The German language has an expression that corresponds to this. A German
might say:
Well, I'll go to Buxtehude! (and no, I don't know why it's Buxtehude!)