Degree in chemistry, then PGCE.
You'd need to do a PGCE, but even then I know our science department wouldn't take you on unless we were beyond desperate. We've found over the years (and through bitter experience) that the best teachers tend to have a degree in physics (or closely related, like astrophysics), biology (again, really closely related ones like zoology are fine), chemistry or biochemistry.
We now ignore applicants who have degrees in psychology, geology, sports science etc., even though they've all got PGCEs, and have often done an extra year to top up on one of their sciences. I'm pretty certain we'd ignore someone with a nursing degree. I'm sure there are exceptions, but at our school, they've always ended up leaving teaching after 2-4 years, mainly citing workload as the issue.
You need to check with whichever universities you'd do your PGCE. However, be warned, the universities may be happy to take you on, but then you may find that once you're trained, schools aren't so keen, and you struggle to get a job.