Well you can get the address from the website, so I suggest you go on Google Steetmapand check out the location.
I don't know if there is a rear entrance but the front door is next to three takeaways and there are always people hanging around outside them so be prepared for some banter as you enter or leave. There is also an industrial sized CCTV camera watching that area, it may or maynot be owned by Bay Massage.
On the up side, it has been there for 10 - 15 years under different names, Number 19, Heaven, Mystiques to list a few.
There is street parking but you have to get a ticket from the meter, the first hour is free but you do have to enter your Reg Number.
As to the quality inside I have no idea as I don't fancy the walk up.