Mr B .
All airlines, at times, expect you to work on a day off. Some pay fair compensation , others don't . In all cases you can decline if you choose.
The difference is; at BA YOU ARE CONTRACTURALLY BOUND TO WORK if req'd.
You also wrote...
get on with life instead of fretting about how many weekends you haven't had off.
Well, lets wait till you have children and see how you feel . Please email me after you have done a year or two at BA. Perhaps by then, you will have removed the rose coloured spectacles. You will be through the honeymoon period and we'll see how you are coping then!