1. I plan to fly bmi to LHR and then UA to LAX via SFO (for the extra 800 miles!). It is 100 quid cheaper if I book both flights seperately i.e. MAN-LHR on flybmi.com and LHR-LAX on ua.com. Doing it this way will I be able to check-in through to LAX at MAN? If not can I check-in at the FCC - does united have a desk there?
You will only be able to check your bags through to SFO, as you have to clear customs at the first point of entry into the United States. They should, however, be able to at least tag your bag to LAX and issue your boarding passes all the way (although sometimes I've known them to have problems doing this).
Yes, United have a desk at the FCC.
2. Any tips xfering through LHR to T3? Realistically how long from T1 to T3? I have two hours from touchdown to takeoff - should this be OK?
That should be plenty. Typically, buses run every 5-10 ish minutes, and take up to 5 mins to get around to T3 (they use the behind-the-scenes tunnel routes). You can, if you have plenty of time, do the underground tunnel walk, but the buses are probably your best bet.
3. Red Carpet Club - as *G I assume I can use the lounge at LHR. What about at SFO when on the domestic segment - don't all American airlines have funny rules about not allowing access unless you have an international flight? 
There is no such restriction. I use my *G to use United RCC's all the time. There is no stipulation on type of flight at all - you just have to be travelling with them on that day. Show them your card on entry.
Last edited by preiffer; Jan 3, 2005 at 4:05 pm