I live in a purpose built flat conversion. My neighbours above

Hi
Thanks for your reply.
The first thing to say is that you are under no legal obligation to actually agree to this and also execute the deed of variation giving ownership of the loft to them. If you don't want to do it you don't have to, but it may mean that the sale of the property fall through and obviously this could damage relations with the sellers.
I would certainly consider getting a solicitor to look at the deed of variation to ensure that your ability to enjoy your property and ensure that the repair of the building as a whole will remain satisfactory. Most specifically you want to check that the repair obligations for the loft are sufficient and that you can enforcement.
The second thing that i would say is that you should get them to pay for your solicitors fees to examine the deed of variation.
Depending on your thoughts on approach to the situation and the fact that you are not under a legal obligation to agree to the deed of variation you can consider charging a fee to execute the deed of variation. What you wish to charge it up to you, but they are free to reject auto accept the offer.
You should bare in mind during negotiations that it may be that you require them to help you out in a future sale that you might arrange in the future if you require that the term of your own lease is extended. They could cause difficulty later for you if you need their consent if you act unreasonably now.
Kind regards.
Tom