Hi needing some advice about UC please :)

Hi everyone, i have been claiming universal credit for almost two years as part of a joint claim (my partber works but i dont) i havent been able to work at all for almost a year and was told that because my partner earned a set amount i didnt need to take part in work related activity, my arthritis has gotten alot worse and chnages to my medication have made me a mess if im honest, so a few months ago on the advice of my doctor i started getting sicklines for to hand in to the dwp as he suggested i would qualify for help.....i filled out my form and have just had my medical assessment, but ive been reading about the next steps, if im found limited capacity for work will i recive the extra money as my uc claim started a while ago or not, or if im the higher rate does that get added on to my uc? Do i apply for PIP or is that included in the UC, the jobcentre have been quite unhelpful, i have a appointment with them on monday for a work search review whilst waiting for my decision on what group i will be in. Any help appreciated! Thanks