What a bad experience! I can honestly say I've never come across this with BA, so I suggest you vote with your wallet. And Jet2 is one of the better LCCs too. My commiserations to you.

I am sure the reason for the LS169a / LS169 tactic is that if you apply for compensation under EU regulations, Jet2 will say you didn't have a cancellation, but a delay. Then you can see the Sturgeon threads to see that delays get duty of care, which I can see is arguable in your case, but not compensation. Even if/when the Sturgeon appeal is thrown out I've no doubt Jet2 will claim exceptional circumstances (if it's partly due to crew going out of hours then that would be fairly weak). See Panny's recent thread over in the Emirates forum, for example.

So in your shoes:
1) I would claim on my good quality travel insurance, which I'm sure you have too! That's what travel insurance is for.
2) You could try to claim consequential losses from Jet2, but I don't think they are legally responsible for that. BA have been known to make a contribution in some situations, but I don't think it's a given. Two telephone calls will be covered by the duty of care regulations. Personally I would have bought the food onboard and charged that back to them too.
3) By all means approach Jet2 under the European compensation regulations, but you probably will struggle to get that. Even if the appeal is thrown out I forsee a lot of letter writing (at the very least) and you will need to ask yourself how far you will go with that.

There is an element of this going with airtravel, and a degree of "you get what you pay for". I agree it doesn't excuse Jet2's inability to keep you fed and watered.