I have now seen the ad and can confirm that the 2 girls, both well known actresses, are Katherine Parkinson (no boobs) and Amanda Abbington (boobs).
Of the two, Amanda is the better known with a CV which includes recent stuff like the Booze Cruise, The Robinsons and Man Stroke Woman. KP was in the IT Crowd as well as Martin Clunes' dippy secretary in that comedy where he plays a doctor in Cornwall.
...er,nope,sorry...but the message I got from the ad was 'be careful WHERE you eat these gorgeous chocolates,as you don't know WHAT they'll make you do'...heheh...I work in a Coronary Care Unit here in South Wales..I shudder to think what could happen if I did something like that...it could cause further heart failure....teehee....(or get fired..mwahh)! Just kidding, I'd NEVER do something like that!!!