Parent wants to downsize

So my dad is due to retire with no private pension. With these new proposed planning laws coming in hopefully soon, He has asked me if i would take over the family home and we would build a smaller house in the garden for him to downsize to. Im looking to get a mortgage or large loan to fund this build and do up the property a bit like heating/new windows etc. My dad thinks its easier if he puts the house in my name and then get a loan using the house as security but im wondering is it better to mortgage it and buy the house offically? Im currently renting and saving the 10% deposit will take me a good while yet.

Just wondering if anyone has done something similar or plan to this year? Is there any grants that will help etc. I will take all the information i can get before i decide to take him up on his offer.