Personally I'd pay the bit extra and go straight through to Manchester.

Road and rail transport is ridiculously expensive in the UK....nevermind the nightmare of getting out of London Heathrow or Gatwick and on to your final destination.

I've flown both Etihad and Emirates on that route this year, and both are good airlines.

Just watch out for length of transit time at the Mid-East airport, if you want to keep the flight as short as possible.