How passionate are you about geophysics then? It's an awesome subject and, in case you were wondering, is extremely employable (geophysicists are in extremely high demand by many top oil/gas firms, at the moment).
You won't be able to do a joint honours with aeronautical engineering, but you do have the following options:
1) You take a meteorology/atmospheric science degree, where you get to understand the physics of winds on all atmospheric levels, including jet streams, as well as climate. This does have some ties with aeronautical engineering.
2) You take a Geophysical Sciences degree (at UEA) or a Geophysics & Meteorology degree (at Edinburgh);
3) You take a pure (geology &

geophysics degree.
and then you could follow up any of the above with an MSc in Aeronautical Engineering, provided you have the right amount of maths and physics.
And don't worry about being 'passionate' for a subject - a lot of people don't have their passions sparked until later in the degree. What's important is that it's a subject you can see yourself studying everyday for the next three or four years and can cope with academically (i.e. since it's physics-related, problem solving sheets, intense mathematics, etc).