When completing the HGV medical for D4 you are asked if you’re taking medication to lower blood pressure but I wouldn’t think your reading would be a cause for concern for the DVLA.
I believe Propanolol is a beta blocker, as far as I’m aware taking a beta blocker will not stop you getting a HGV licence but it will need to be reported on the medical form, as long as the medication is doing it’s job and reducing your blood pressure to an acceptable level I don’t think there will be a problem.