Do you have to give up your Green card?
 

We are possibly moving back to the UK from the USA next year - if we can decide that is the right choice for us ( thats a whole new topic!)

I was wondering if we have to give back our Green cards. If we dont give them back and then take a holiday to the USA after about a year, will be get turned back at border control? Will we need to start getting an ESTA again? Just wondering what we should do - thanks for your help!

Re: Do you have to give up your Green card?
 

If you leave for more than 12 months they automatically cancel your status as a permanent resident, the green card is just evidence of the status not the status itself. Many people hold onto the card like a souvenir. If you come for a vacation you'd have to apply for the esta like everyone else.
If you want to keep the option to come back open for longer, you can apply for 2 years outside the US, I forget which form it is, you'd have to google. (I think it's an I 131 reentry permit.) With this option you could come back using the green card to enter on a vacation as you'd be a returning resident for 2 years.

Re: Do you have to give up your Green card?
 

You do not have to surrender your Permanent residency status or cards when you leave the US. However, there is a formal process to do this known as "Abandonment of Lawful Permanent Resident Status" (link here) whereby you fill out a form and return the PR cards. The reason you might want to consider this is that as PR's you continue to be liable to US taxes even if you are resident outside the US. Also doing so may reduce confusion at the POE if you try to enter the US using the VWP later. Of course, you may want to wait a while before taking this step to keep your options open.