Blow/sod that for a lark British spoken language informal slang
Blow, sod or bugger can substitute for each other without changing the meaning.
To stop or avoid doing something because it demands too much effort
Sod that for a lark! I am wasting time on the impossible thing. I give up!
Well, just blow that for a lark! I'll move all the food parcels at once instead of carrying them over many trips.
Blow that for a lark! I don't want to cook. Let's go out for a meal.
Bugger that for a lark! I prefer staying at home to going out in this snowy weather.
Knit a scarf? Blow that for a lark!
Adequate measures or actions
To do one's best or try one's best to do something
If you desire something good or appealing, you must make the necessary effort to acquire it.
To work really hard in order to attain something.