Just FYI:
This may be an example of why doctors should not arrange MRI without clinical signs of nerve compromise - firstly, there is no way of telling whether the L5/S1 bulge is new or old (and if it's old then it's completely unrelated), and secondly no competent surgeon would perform surgery for pain alone.
Even if you had good going pain in an L5/S1 distribution (which might suggest it's acute), without objective signs on examination the MRI, and then the surgeon visit, may have been unnecessary.
Of course, maybe your GP found signs when they examined you and everything done was completely appropriate, but it's increasingly common for patients to demand MRI scans when often many doctors don't understand how to interpret the results. This inevitably leads on to referrals to either surgeons or people like me (Neurology).
It's a big expense on our health system, so even if this doesn't apply to you I hope it helps someone else be investigated rationally.
At the end of the day, the natural history of acute disc prolapses is variable - some will recover really well (with follow up scans showing disc almost completely back where it should be), and some do worse or somewhere in between.
I think following the advice of your physio sounds sensible, and just avoid activities that exacerbate it.
Hope some of this helps.