I’m thinking of going to full time hours what should I do

Hi guys
I have a disability from a spinal surgery I had 6 years ago I live with chronic pain all the time. I was awarded my pip benefit a couple of years ago and I work part time (just a school mini bus driver) but that job is coming to an end and I’ve been lucky enough to find a full time job working for a mobility company, still driving but now delivering aluminium walking frames etc what do I need to do regarding my pip I’m worried that the change to full time hours will end my pip claim, I still suffer from chronic pain but I’ve found that sitting around makes my pain worse and that moving about regularly a little bit actually helps. The pain is bad overnight and first thing in the morning I’m useless for a good hour when first getting up (luckily this job starts at 9 so I can get up about 0730 and use my first hour freeing up my back and getting dressed etc (that takes ages as I need one of those sock gizmos to put my socks on and a long handled shoe horn to put my slip on shoes on, so whilst the full time hours delivering bits of mobility aids to people like myself is good, I still need special measures in place ( late start times and dressing aids, shower aids etc) to be able to manage daily. My real fear is that I’ve worked part time driving for years and I’ve no idea if I’ll be able to manage a full time regime or indeed how it will effect my pain and discomfort levels. If I phone DWP and cancel my benefit ( I don’t even know if I have to do that) I may not manage the job and have to reapply for pip all over again. Can anyone help me with advice on what to do
Thank you
Ged