Not sure about the avios reward flights but Hotline tickets do count toward Exec Club status and there are many cabin crew Silver Card holders out there. Hand Baggage Only fares can also work out relatively cheap (relative to ST). ST does not kick in till after six months.
There are also several crew boarding houses that cater for commuter night stops as well as Premier Inn, Jury's Inn etc staff rates.
As a junior bod you would have no control over trip lines but trip swapping is possible, and there are enough tours where BA would pay for the hotac. Reserve months can be a pain for commuters as you may well be on Home Standby which means two hours to report from call.