Phew indeed! Thank you everyone for your comments and concerns.
Geetak's comment regarding gift tax got me researching the subject and I've learned a few things. First, it appears a family member can loan another family member up to 100,000 USD as long as it is deemed a loan (with some written agreement), and has an interest rate at least as high as one set by the IRS. Then, it is up to the lender (my parents in this case) if they wish to actually ask the debtor (me) for this money OR claim it as part of the 11,000 gift allowance. So for example, if the loan is 100k and the interest is 5%, the interest would be 5k (easily under the 11k limit) and could presumably be forgiven if they chose to do so.
Regarding inheritance tax in the UK, it appears that as long as one parent survives for 7 years after the money is given, this is not considered inheritance.
More information can be found here from H&R Block:
newcomer link: http://www.hrblock.com/taxes/planning/planning_101/loans_to_family.html
[nonactive] It also seems fairly common in the UK for parents to freely loan their children money for purchasing a house:
newcomer link: http://www.thisismoney.co.uk/mortgages/mortgages/article.html?in_article_id=406361&in_page_id=58
[nonactive] This is all seemingly helpful information and solidifying in my mind that, with the proper documents drawn up, this shouldn't be too difficult or in any way illegal. BUT if anyone thinks I'm being naïve and misunderstanding this, please do warn me. Let the thread continue.
Thanks again
* Just a note about the potential for my parents purchasing the house - it doesn't appear to me to be an option. They reside in the US and with today's house prices, their contribution will 'only' be approximately 15-20%, my wife and I will need to come up with the rest.