Using 2 passports

can i travel to different countries during my stay in the philippines using a british passport?

I mean, i am planning to go to the philippines for 6 months using a british passport (im a dual citz) and in between the 6 months can i go to hongkong using the brit passport or do i have to use my phil passport?

you can leave on your Filipino one and enter Hong Kong on you British one whatever suits you best

You can certainly use the British passport. If you use it to go to Hong Kong, you can stay there for six months, instead of the two weeks that you would get on your Philippines passport.

Also I think that if you travel into the Philippines on your British passport you will get a balikbayan stamp which can be useful.

If you are Filipino / British dual you dont need a balakbyan

I

I was thinking of the duty free privileges

Thank you both! Also I want to know, what will happen to my N.I when I leave obviously I will be away for more than 3 months. Do i need to do something about it?

You can either arrange to continue to pay in, by standing order, which few people do but which is probably the best plan, or pay a lump sum when you are back, or leave a gap in your record. I don't recommend the last option as it may seriously affect your pension.