@HK visa

Hi, I'm going to Hong Kong to spend the holidays with my husband and in- laws from UK. I have already booked a ticket for 4 weeks. Originally planned to book ticket for 14 days then extend at the HK immigration in Wan Chai few days after I arrive. But the price for the return ticket is very very expensive. I go to Hong Kong once a month and never exceeded 14 days and have never tried the extension. Should I apply for a visa here in Manila before I go? If I don't, will I be rejected/questioned at the immigration? Thank you so much in advance.