you are in the UK so what I post may be different for your location..

here in america we have two different words...

dis association and dissociation

the differences in the two words....

disassociation (with the a between two s's) means to purposely some one self from doing something example I disassociated from making the bed meaning I stopped making the bed.

dissociation means to feel numb spaced out and disconnected from one self or those around you. here in america this is a normal response to a trigger...

you know how if someone says something you dont like (the trigger, the cause) the normal response (affect) is to feel angry.

well with dissociation something happens (the trigger, cause) to make someone feel numb, spaced out, disconnected (what the trigger made a person feel (affect)

from there depending upon severity the normal dissociation moves into being a disorder (you can read what dissociative disorders America has at this time in the links at the bottom of my post)

please remember only your own treatment provider can answer as to what they meant when they said you have disassociation problems.

my suggestion is contact your psychiatrist and let them know you dont understand what they said you had and would like more information of what they meant.