Welcome to the forum Amon. There are plenty of Filipinos living in and around Cambridge, as Terpe said, a large number work at Addenbrooke's hospital so that might be a good place to start. There will no doubt be quite a number living in Cherry Hinton too so you might like to check out the nearest catholic church as well.
There is a Chinese/ Malaysian supermarket called Cho Mee in Cambridge which also sells a few Filipino products, such as longganisa, papaitan, bangus, tilapia, bagoong, noodles and lots more. It's located at:
108-110 Mill Rd, City Centre, Cambridge CB1 2BD
I haven't been there for a while so not sure of the opening hours these days but their telephone number is 01223 354399 should you wish to check. When I last went, there was a Filipino guy working there too.