You have to inform DVLA of any medical condition that your doctor believes would affect ability to drive.
I have slow "digestive transit" (there's posh) but it has not been a much of a problem since I retired. The house has three toilets so a bit of non regularity is manageable. The biggest problem seems to be when I have to attend for the Bowel Cancer Screening Program. Four times now and they still have never managed to empty the colon with their el zippo laxative. Each doctor has put "needs more stuff" in the notes but so far I still get complaints from the foot of the surgical table from the bloke holding the camera on a stick.
That's less of a problem now since I have completed round one.
I have finished the official program now so that's another problem out of the way. During the program, at each examination the doctor wrote that I need more stuff for next time. This year I got one week of mild laxative then the big sachets (two of) at the end of the week. Only now has the doctor written that I need three sachets. Then I got a letter saying I have completed the program. Good ere ennit.Just ask your GP for more!! I had tecent tests again and instead of taking the 5 senna tablets for 2 days and one day of citramag I was allowed to add in picolx and started at 5 days..
Shame they also booked me to have my repeat slow colonic transit test the same time and it had to be altered.... Then had to have 10 days in total with no meds...
If you have slow transit. Amutiza can restart colon a little but that helps, also dulcolax. And low fibre foods...and a back up / reserve of picolax to take to save A&E admittance.