Make sure you inform the bank that your going to the Phils and for how long as they could stop you using your cards otherwise.
As I would not be able to distinguish counterfeit notes I would not use a changing kiosk. I choose not to travel carrying large sums of cash in any currency, hence my policy whenever I travel overseas to anywhere in the world, is to take a minimum of local currency with me for immediate needs after arrival and ATM's after that.
I'm sure that's what most people do. However, as I and others have mentioned, in the Philippines at least, I have found that I was able to get a better exchange rate from the currency exchange at NAIA arrivals than I could in the UK.
Use a reputable money changer, @joi1991 in an earlier post said that Western Union was not the best value. From my experience Western Union moneychangers in Manila, Tacloban, and even Manila airport (T3??) take 2% commission on top of the interbank rate. ATM's: Your UK bank will typically charge about 3% on top of the interbank rate. Philippine banks charge an additional 200 peso for using a foreign card and might only allow withdrawal of 5,000 or 10,000 peso.
Personnally, I can recommend money changer in customer service of all SM branches. My sister from US,cousins from Ireland and dubai used them. They have good rates ... But be patient enough to write the serial numbers in the form
There's a jar in a cupboard in Ilocos. I left it there in 2014, and I'm SURE it will still be there, judging from the looks on their little faces when they tasted it.