Yep, agree with the Ferret. I wanted LH when I joined, was A320 rated and was offered and accepted a start date for SH as “no LH places available”. The next week 4 guys from my base at ezy got offered DEP 747. Just the way it is. Get a start date, get your seniority number and after 5 years you have a lot options.
A LH DEP will be disproportionately junior for much longer than someone who does the initial freeze on SH. Whether that is a price worth paying to bypass the A320 rostering is down to personal circumstance/prior experience and, most importantly, perspective. Seniority is everything in BA. I can’t see that changing any time soon.