Return flight or one way ?

I have a particular popular home in Florida being held for me for a short time for next Sept/ Oct until I can confirm exact days of my flights. But I have to act quickly. I am looking to fly out about 20th Sept but obviously I cannot book my return trip until the flights are released in November. Should I try to book my outward flight as soon as possible ( am hoping to use miles to upgrade PE to UC or at least a Z fare) then hope to find a Z code return flight in due course ? Or will these two separate bookings make it much more expensive and I should wait ( & keep fingers crossed) to do a round trip booking all in one , please ? Once , in the past, by the time I was able to book my return trip the outward seats I had hoped for had gone.
Thank you.
hiljil

One way flights are much more expensive that booking a return.

If you want your eyes to water do a couple of dummy bookings just to see.

There is a 'trick' and I have not done this and there are some risks where you book a return flight (UK-USA-UK) but don't use the return sector. Then to get back home you book a return (USA-UK-USA) and use the outbound to get home then disgard the trip back.

The airlines dont like people doing this though.

Thank you. I somehow feared I would be making a mistake by not booking a round trip. I really appreciate being able to ask someone who knows.
Regards
hiljil

[Neil]

If I were you, I would confirm you holiday home and be pretty confident you will sort the flights out. Sept/Nov aren't the busiest periods, you will have the option of MCO from MAN or LGW and also MIA (plus you could worst case do NYC/BOS and then an internal to MCO), so I would imagine one way or another you would get them sorted.