totally confuzzled with what to do!

[JawsMew]

Help!
I was asked to rehouse an elderly couples tort. I agreed when I heard that all he need was a dog kennel, weeds and lettuce. They had him for 40 years and rehomed him from their neighbours who moved. Since agreeing to have him / her I of course wanted to know more and make sure that I gave the tort the best care. Sooooo since posting on here and reading I feel unbelievably nervous and worried. I have brought a wooden outdoor tort house which he can go in and out. He has free range in my walled garden ... complete with weeds. But I am just concerned that I do not have space indoors to have a set up for him as the more I read the more I am thinking I should have a lamp for him to bask under. I was told he was an Algerian Spur or whitei or Graeca Graeca (still getting my head around species). He is a lovely size and has been eating and trotting around my garden.
I feel such a huge responsibility for him. I gave this elderly couple my word that my home would be his forever home and I would always look after him. I am willing to learn and invest time into his welfare. I just want him to be happy.
What would you do? How would you set up his home? Would you keep him outside all the time like the previous 40 plus years? Would you give him access to a lamp? Can you use a lamp outside? I am more nervous looking after him than I am when my own c hildren were born! I would never forgive myself if I didn't care for him properly and this has an effect on his health. I have only had him a few days but my heart is already bursting with jelly beans when I look at him. I am in love.
<a href="http://s1273.photobucket.com/user/Karah_Mew/media/Mobile%20Uploads/20140417_161006_zps7c0762a4.jp