Apologies, I completely misunderstood your question.
The default US layout will not give £ or € by default. US International will (pound becomes AltGr + Shift + 4, euro AltGr + 5)
US Int has a rather annoying 'dead key' system. This is where, in order to facilitate accents, certain keys will do nothing when you press them the first time, and upon subsequently pressing an appropriate vowel, the accented vowel will appear. This means that in order to get the character by itself, you have to press the key and then spacebar. For example, the single/double quotes button is one of the affected ones as it used for umlaut accents, and given how often you'd use this key, it gets really annoying.
Someone around here made a version which ditched the dead keys, and implemented accented vowels using AltGr, which is what I use on my Windows machines. If you have Linux and are running a GNOME or KDE desktop, this layout is built in as the 'US International (AltGr Dead Keys)' layout