Thanks for the recommendation. Recommendations re brands for this sort of thing from someone experienced are so valuable!
Earlier in this thread people suggested this sort of profile (but I think they didn't realise this is a very simple application, just a bog standard casement).
My slight concern with this sort of profile is the likelihood that the edges might fray a bit over time, whereas a bubble seal doesn't actually present an edge as such to the (fixed) frame where it's meant to make the seal. Also that the ability to spring back ("memory") might decline over time. Maybe a good brand will be better than I imagine.
This page suggests Schlegel have given matters a lot of thought.
I can imagine that the seals you suggest might cope better with a gap which varies slightly along the length, and maybe cold air is likely to get through more easily with a bubble seal.
Schlegel also seem to do
an interesting one which doesn't have a "frayable edge".
hmmm