"Roger, G-ABCD" is the only correct response I would use.
There is no such correct phraseology in CAP413 as those you mention above. If you want to change this, by all means offer your concerns to the Safety Regulation Group who may devise a more appropriate response for inclusion in CAP413.
You are both VFR I assume? In which case the responsibility for separation from each other lies with each aircraft, not the controller. Once he has passed traffic information, this is his task completed in effect, and he would naturally assume after you reply "Roger" that you will be making an effort to look out.
That's not to say that your non-standard phraseology wouldn't actually enhance the safety of the whole situation. I would however avoid use of "contact the traffic" as the word "contact" generally infers a frequency change.