Although I love a crusty ham salad cob on a picnic, one of those Italian sandwich thingies is lovely and a bit special - they travel really well and improve with a bit of keeping, although it takes a bit of pre-prep (if this is what you mean by faffy, then I apologise, I was thinking more in terms of no faffing at the picnic itself!).
You get one of those rustic round loaves, slice it horizontally into 3 or 4 (depending on height of the loaf), then layer your choice of cheese, meats, salad leaves & roasted veg in between. Wrap up in foil and weigh down with a scale weight/heavy something in the fridge for an hour or so to let everything meld together. Cut into wedges on arrival at destination. Lovely!
Last one I made I used pesto and butter/olive oil to spread on the cut bread, then layered ham, sliced emmenthal, roast red/yellow peppers, rocket/watercress, brie, cherry toms and thinly sliced chicken. Yum Makes far too much for 2 people unless you're not eating for the rest of the day, though... We're not salami or garlic sausage fans but the original recipe layers them on (and sliced roasted courgettes too, but that was a faff too far - at least you can buy the peppers in a jar or tub pre-roasted!)
Hard boiled eggs with a shaker of salt. Cold chicken & ham pie/cornish pasties/bacon & egg pie/Nigella's pizza rustica alla Inglese (posh sausage/bacon/egg pie) with an accompanying jar of chutney all travel well. Banana bread or LDC baked in a loaf tin is good to take and slice up at your destination.
I second the strawbs, with clotted cream is good for travel as it won't slosh about.
Please don't take Kettle Chips, even if you are posh. Union-bashing barstewards...