As someone who has actually been denied entry to the UK (despite having a return ticket and real intentions of returning to the States at the appointed time, only one month later), everything you're saying sounds like a huge red flag knowing what I know now.
First of all, I agree with everyone else, you absolutely have to have a return ticket. Beyond that, I really think you need to plan on going back to the States on your return flight until you have the proper visas (which I think you have to get while in the US.). . .And, even though you're technically allowed to be in the UK for six months as a visitor, I would set the return date sooner than six, because that in and of itself may be a red flag.
Secondly, I would not lie about who you are coming to visit because, if you are the least bit suspicious, they are going to ask you for information about these "friends." Like names, addresses, telephone numbers, physical descriptions, etc. And, if you aren't prepared to give it, you're going to find yourself in a world of trouble before you even know what hit you. (Speaking from experience here, so trust me.)
Third (and maybe most importantly,) crabbit.expat is right. Actually, I'll go even further and say that I would bet that mentioning that you're looking for work will almost definitely get you denied entry. So, I wouldn't mention it if you decide that's the direction you want to go. Technically you aren't directly telling a lie. Just withholding some information.
And, finally, make sure your boyfriend is in the airport building to pick you up. Part of my customs debacle was that my now husband couldn't hear them paging him over the PA to answer their questions. By the time they found him, they had already made up their minds that they weren't letting me in anyway.
By the way, my husband is over on a work permit, and I have to chime in with everyone else and say that they are very difficult to come by unless you are in a very specialized profession. . . . Is there any way you could come over on a studen visa? Or, I think there's also a Working Holidaymaker visa for people under a certain age to come to the UK and work for like a year or something. That would at least get you over here.
Sorry I couldn't be more positive, but I would hate to see someone else go through the ordeal I went through.
Good luck!