Thanks for your enquiry.
In order to remove your Charge/CH1, you do need to submit a DS1 Form. You shouls be able to prnt this off the Land Registry website, or you can instruct a local Solicitor to prepare it and submit it for you.
It normally takes the Land Registry between 3-5 days to remove the CH1 from the Register.
In the meantime, there is no reason why your son in law can't make progress with any new Mortgage. It will take time for the Bank/B Society to issue the formal Mortgage Offer and as long as the CH1 has been removed by the time the new Mortgage completes that will be fine. As regards XXXXX XXXXX name to the title, again, this will take a couple of weeks for any Solicitor to sort out the necessary paperwork, so hopefully by the time this is done, your Charge will have been removed.
I hope this answers your question, but if you require any further clarification, please let me know.
Further to my previous post, can I assist further?