What do you do with your UK property when you move to the US?

It's not a good time to sell, so we were thinking of renting our flat out if we move to the US, then sell someday when we could get a good profit off of it.  But I've just heard you need to get a consent to let from the bank and they have to renew it every year!  Dh just saw online someone saying they did it with Halifax (who we have our mortgage with) and after a while, they just cancelled the consent to let and made them go to buy to let, which has a way higher interest rate! 

I'd be so nervous the mortgage payments would go higher than the rent, and then what the heck would we do??

Yes, we are wondering what to do about this......We are waiting to hear about ILR and if we don't get it we will need to go back-----but after talking to estate agents and looking at getting less than we paid for the house (after fixing it up) we are really depressed.  Do I understand that the mortgage company will have to approve to let?  we are only on a variable rate now---is the interest rate for our mortgage likely to go up if we let?     anyone want to buy a house and car in the midlands?.......