So, between 1711 and and 2256 yesterday you went from only wanting to join the RAF if you could fly 'large cargo aeroplanes' to seriously considering a career as an airman/NCO mechanic ?
Don't rush into anything. Can I also suggest that getting into the RAF in any capacity is not just a matter of signing on the dotted line. No doubt they will want to see that you have given the matter some serious thought (more than 6 hours worth) and that you are prepared to commit to a good number of years service.
Bon chance.