Firstly, where in London are they moving to (roughly, I don't need details)? It makes a huge difference to what's easily available. I live in east London (Walthamstow) and there's very little you can't buy in local supermarkets or in the markets.

But on the whole -

Flour tortillas - most large supermarkets (like Sainsbury's) sell a ready made version by a firm called Old El Paso.

Salsa - you're kidding me? 1 can plum tomatoes/medium size onion/clove of garlic/tinned or pickled chillies to taste. stick in a blender - voila!

Green enchilada sauce - no idea but they may sell a version with the Old El Paso stuff

Green chillies - tinned or pickled over here - mainly Turkish/Cypriot supermarkets are your best bet depending where you are in London.

Jell-O - Jelly - Normally fruit flavoured over here - best known brand, Rowntrees. You can get veggie versions (no animal extracts) and sugar free versions in most supermarkets.

Marshmallow fluff - used to see it regularly over here but it's died a death - best bet ex-pat shop.

Mogen David wine - what's that? Alcoholic? Wine vinegar?

Beau Monde Seasoning - the recipe given up above should be a snap to round up the ingredients for. Best places to buy fresh and cheap spices in London - Indian, Turkish/Cypriot supermarkets. Usually sold in roughly 4oz bags and upwards (my local supermarket sells paprika in kilo bags!!!)

If they're moving into or near a very Jewish area (Golders Green, Hampstead Garden Suburbs etc.) they'll find a lot more american style stuff.

Just chuck me a pm if they need specific locals etc. for stuff.

TTFN Lady P.