I have a horsefield, had him for around 2 years now. Its come to my attention that I've been given poor advice repeatedly on how to keep him and I'm worried about it so here I am to try and put it right.
First of all the place we brought him from gave information to feed him normal household items such as cucumber etc, I found that was wrong so I've been feeding him things from the garden (dandelion leaves/flowers regularly and the odd other thing like rose petals and other leaves that I've found here that is ok to use)
Usually George is quite the greedy boy (could be female) and eats everything I give him.
I have him in a glass tank which I know isn't ideal but it does have a mesh roof for air ventilation. UV is kept on for 12 hours a day, so is his basking lamp. His basking lamp is kept at one end of his tank (4ft) to provide space for him to go if he gets too warm.
I was told recently that because of it being summer I can lower his asking lamp to a 60W bulb because of it being warmer. Since doing this he's been quite sleepy and after googling I've read that because my room being none sun facing he might be too cold and thinking it's time to hibernate. I changed his bulb back yesterday.
This morning I removed him from his bed and put him under his lamp where he seemed a little more alert than he has for the last week or so. He pooped and I moved it somewhere else in his tank to remove it later (when my toddlers sneaky hands were further away)
When I came to remove it I noticed it was full of white worms! After googling I found to see them in the feaces means they are really contaminated

I called around and found a reptile vet and have just come back.
He's told me the way I'm keeping him has made him ill. I was advices previously that top soil from a garden centre is fine to use for his habitat, but the vet advices me otherwise because of it being full of germs and bugs etc and that's why he probably has worms

I'm unsure what to do now as the vet gave very mixed advice, he told me I should be using wood chippings snd when I said that I'd read that isn't true he said I can buy dirt from pet shops?
What should I be using?
He hacked him over and said he's a lot smaller than he should be and that his shell isn't as sturdy as it should be too.
Please help me, I want to keep him healthy and happy.