Travel on nearly expired passport

I am a US citizen living and working in the UK for the past 3+ years on a Work Permit. My Work Permit is valid until 2014. I have just booked a 1 week summer holiday to Spain, but didn't realize that my passport is expiring soon. My passport will have a couple of days more than 5 months remaining at the start of the holiday and a couple of days less than 5 months at the end of the holiday. The holiday is in 3 weeks.

I guess I have three questions.

1. Will I be allowed into Spain?
2. Will I be allowed back into the UK?
3. Is it too late to renew my passport?

According to the US State Department website:

ENTRY / EXIT REQUIREMENTS FOR U.S. CITIZENS: Spain is a party to the Schengen Agreement. This means that U.S. citizens may enter Spain for up to 90 days for tourist or business purposes without a visa. Your passport should be valid for at least three months beyond the period of stay. You need sufficient funds, evidence of hotel reservations or an official letter of invitation if you will stay with family or friends, and a return airline ticket. For additional details about travel into and within Schengen countries, please see our Schengen Fact Sheet. For details regarding what is required for an official letter of invitation please visit the website of the Spanish Embassy in the U.S. 

(http://travel.state.gov/travel/cis_pa_tw/cis/cis_1024.html#entry_requirements)
So you should be ok. I think you'll be ok to re-enter the UK because of your visa. Have fun! I love Spain a lot so I'm jealous.

Adding to what Aimless said, according to this, Schengen countries only require three months and the UK doenst have any minimum requirements.

All of the countries of the Schengen Agreement — 25 European countries, which is most but not all of them — require only three months' validity after exiting the country. Note that the United Kingdom is not on this list; in the U.K.'s case, any valid passport is accepted with no minimums enforced. Policies among the European nations not in the Schengen Area vary quite a bit.