I moved house and had to do this recently, one thing I would say was that my new hospital would only allow a self referral at this late stage if I was registered with a local GP. If you’re going to do it I’d do it asap as you have to do all the booking appointments etc all over again and it’s not always the quickest process x
I also moved recently so had to re-register with a new GP and hospital. It’s caused all sorts of confusion and took 6 weeks to sort making me miss the GD test timeframe (due to some admin mess up) so i would say sort it sooner rather than later if you want to x
You just need to refer yourself again, you’ll need another booking appointment in Manchester and then they’ll take over ante-natal and delivery etc x