To be honest, as crew... The amount of wedding dresses, suit carriers, clothing carriers, hat boxes and odd shape items that I have to try and fins stowage for on a small airbus, I really do not think you will have anything to worry about. This is at LHR, not LGW, so can not comment too much on security at LGW, but I am sure you will be more than fine. Hundreds of people a day get stuff onto the aircraft, I am sure you will be able to too...
Just make sure it is well protected, i.e. covering as I am sure the crew will try and hang it somewhere for you (I hear the wing is great for airing clothing items en-route
) but there will be other items hung along with it, so just to make sure it is not marked by any other clothing or other such items placed in there.
Good luck!
