Underfire, AIP ENR 1.5 2.6.3 specifically allows climb before the MAPT. This paragraph is basically stating that if you begin your climb before the MAPT you must continue to the MAPT and then follow the procedure; or in other words don't follow the lateral tracking instructions from prior to the MAPT.
As for traffic at MEL etc? Just say your callsign, "going around" and what you are doing straight away (ie prune 123 going around climbing 5000", let ATC do the rest. If you are coming up the clacker of another plane, they'll probably tell you to turn- "or as otherwise directed by ATC", remember that?
Here's another thing to think about. What is the go around/missed approach procedure in your aircraft manual? Does it tell you to stay level or descend? No, it tells you to climb.
I think all the smart people who know what they are doing (and are safe operators) are all saying CLIMB, don't remain level and hope.