Amanda - you'd have to ask whoever has told you that you need to 'write in' the details you mention
I suspect, but don't know, that if it's your buyer then they presumably want you to include a grant of a right of access and parking in some way. If so then that's where legal advice would be needed
If we've asked you to 'write in' then you should do as requested or respond to the request to query what is being requested.
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