Bkk - Man March 2009

[G54]

I have to leave Thailand late February or early March 2010 to return to the UK for a new 'non O' visa.

I would prefer Etihad for the points on my silver card but am willing to use an alternative airline if the costs and duration of travel are worth it and the service is good.

Manchester or London are equal in respect of my UK travel by train.

Return trip would be 2 - 3 weeks after my UK arrival so would like to book a return from BKK as an open ended from the UK seems expensive (and not sure I can do one) especially as I would expect to be back in Thailand for 15 months on a non O.

Would I be better off making a booking now or best advised to wait until later in the year?

TIA

edit for clarity and extra detail