buttline,
In answer to your question, every pilot joining BA is subject to a 5 year engagement freeze, regardless of type/previous type. There are many many ex-cadets coming up to the end of their freeze this year who will testify this (yours truly included!). Therefore, unless you are lucky (or unlucky?!) enough to be posted directly onto 777, you will have to wait 5 years + for long haul like the rest of us in the queue.
Once you get long haul, commuting is no problem. I have many friends who commute short haul, where there are more issues, but long haul you will be fine.
For what its worth, life in BA is not all doom and gloom as I sometimes feel when I visit this site. There are hundreds of us BA pilots who go to work every day, do a job we enjoy, and just get on with it. It seems to me the most frequent BA postees on this site are the people who are not happy or have a grudge to bear. That is in no way disrespectful - they have their own opinions and are free to post them on here. However, I fly with many relatively happy and content skippers who have never even heard of Pprune (or even t'internet in some cases!), therefore the views you get can be slightly imbalanced. All I would say is remember the silent majority!
Good luck with the selection, and hope to see you at the big BA flying club soon!
Mary