Urgent passport stamp issues

[DharmaBum]

I am headed back to the UK tomorrow and someone just told me that my stamp which I thought was a 6 month visa is actually stating that I have to stay out for 6 months. I cant get to the embassy today and nobody over the phone will help me.

here is the description of my stamp:

One black box with rounded corners that says:

Immigration Officer
(6042)
31 Aug
Luton

and one black rectangle shaped stamp that says:

*** ** *** <--random numbers and letters)
Leave to enter for/until
Six Months
No work or recourse to public funds

But here's the strange part. The immigration office crossed out the word "until" with black ink where it says leave to enter for/until. What does this mean?

My flight is 2 pm tomorrow and I hope to god they let me back in. If not I dont have enough money for a ticket anywhere else. Can I go to the US embassy and get a flight to the states from them?
Its always so much hassle for me to get any travelling done, I was going to go to Thailand but my credit card was denied =(
Thanks in advance!