First you need to see what EBD is worth it for you, i.e. what benefits do you think will make it worth spending extra money? the only benefits worth it for me are: Free same day flight change, free drinks in economy and the give away gold card. But I wouldn't mind to live without them and wouldn't spend extra money to get those - unless being very close to the threshold anyway. But 40k to 50k points on top? Wouldn't consider...

Anyway, probably the cheapest option is to upgrade those London trips to business, take part in the conscious traveler program and take detours like CPH-ARN/OSL-LHR.