Repossession Houses

My dads house has recently been repossessed. We live in the UK. The mortgage oweing is 70K and house is worth £105k. Can anyone tell me when the lender takes it will it be sold at auction or on the open market?

Thanks
Thanks for all the answers so far. Its a horrible situation my dad has been in the house for 30 years. My mom finally forced a remortgage 6 years after they seperated to get her cut when the mortgage was nearly paid. He got injured and on top of mortgage rates going up I think he gave up the fight. The country is in chaos and I wish all the best to anyone in this situation

I got married almost 2 years ago, and ended up living with my parents, with my dads, mum, and my name added to the mortgage.
for the 1st year i was paying £650 a month on 1300 mortgage and my dad was paying the other half. Come 2nd year, i’ve been paying £700 a month, and my dad £600. The thing is that i would like to move out due to personal reasons, with my wife - is there anyway of me removing my name of the mortgage in case repossession occurs after we leave. What would i need to get out of this mess? Please help