busflyer
I'm sure that there are lots of relevant threads that will help you.
A couple of comments, if I may:
1. BA will not offer you a type at the start of the process
2. If your application meets requirements then I would anticipate
being asked to attend the first stage of teh selection process
3. If you pass that, the you proceed to the next stage {see elsewhere for details of the processes)
4. If you pass all of that, you will have the option of expressing a preference as to your destination. I believe we are recruiting onto 737(LGW) and 320,777 and 747 (LHR). Depending on your experience and how much we need people you may get a Longhaul slot even without previous type rating.