Matt,
Large prostate and poor flow are more usually symptoms of benign prostatic hyperplasia (BPH), but can be prostate cancer, so it does have to be checked out.
There isn't much you can do until you get test results, which can make this an anxious time. Typically it takes about 6 weeks to hear.
It might help you to know what's likely to happen. Usually, the first thing is to get called for an mpMRI scan, and then a few days later, for an appointment with urology. Many urology departments operate what they call a one-stop-shop nowadays where you will be called in for half a day or a whole day, to give time for investigations and multiple tests if necessary, to try and get it all done in "one-stop". If the mpMRI scan or a DRE shows something suspicious, they will need to do a biopsy (the mpMRI scan can't diagnose cancer, only suggest where to look for it). It typically takes 3 weeks to get the results from a biopsy, and some hospitals will call you in for a bone scan during that period (which doesn't mean they think there's cancer in the bones, but they have to rule it out).
Hopefully, they'll turf you out with a clean bill of health or suggest treatment for BPH.