Credit card/debit card in an atm is the easiest and probably cheapest - you get pretty good exchange rates and the commission isn't TOO bad - certainly no worse than you'd get by physically changing currency at a bank (all seems such an old fashioned way to do it now).

BPI banks will allow you 10,000 pesos at a time, or 20,000 if your card will stand it. Alternatively, if you're with HSBC and go to an HSBC machine, you can get up to 30,000 or 40,000 (again, depending on your own UK daily limit). Saves having to repeatedly keep putting the card back in the machine - 4,000 in a country which is relatively backwards in terms of accepting credit card transactions (or which still ILLEGALLY charges you 5% higher for using a credit card in many "reputable" - [ho ho] places) wont last you long.

By the way, if you can be arsed, if you ever are charged 5% for using a credit card, then you can:-

(a) - tell the store that you will be reporting them to your card issuer. The terms of their contract with visa/mastercard, et al prevent them from charging you for using plastic and if they do it and you inform visa, etc, they can and will fine/penalise the store. If they still insist (lets face it, the average flunky in a philippine store doesn't even know how his own product works, let alone anything like this...), then:

(B) - send the receipt (tell the store to mark the 5% markup separately on the receipt) to visa and they will reimburse you. Step (B) often works better if you don't try step (a) first - the clueless assistant won't have a clue why you want it identified on the receipt and will happily write down whatever you want to make sure he gets his sale and thus his commission. Step (a), however, does have the advantage of not having to pay it in the first place.

Alternatively, you can do what I always did, which was bluster and rant at the shop assistant, vow to keep my receipt and get reimbursed, and then get home and find I couldn't be arsed, and end up binning it anyway. Sometimes life's too short . Although I haven't tortured myself by adding up how much I've lost in this way over the years, I don't think I could take it.