He's on ProRep Tortoise Life substrate in a table.
He has a mercury vapour bulb; his basking spot was 37C, hot side 35C and cold side 25C but I think that might have been getting a bit warm for him when the ambient temperature goes up so I've switched to a lower wattage one today to see if that helps.
As far as food goes at the moment he's mostly getting a mix of pak choi, chicory, watercress and rocket with some Florette summer mix, dandelion leaves, carrot and red pepper. I sometimes mix in some dry leaf and flower mixes and he seems keen on rose leaves and petals at the moment. I have tried him with weeds from the garden but he only really seems interested in the clover, he just walks over the rest.
He has a tortoise pool for his water that he's able to get in and out of whenever he wants.
He has a piece of cork bark that's propped up on the side of the table that he has dug a small pit under that he sleeps in every night.
I do try to get him outside for at least a part of every day but with him being so small I'm not comfortable leaving him out alone even with chicken wire over the top of the enclosure as I'd never forgive myself if a bird took him or if he managed to find a way to escape; He also (apart from the clover) won't eat any of the other weeds in the enclosure and I don't want him to starve.
And just as an added thing to my original post, his weight seems to have stalled over the last month or so as he has been varying between 65g and 61g when before he would be putting on a bit every week or two.
Those temps are far too hot for a horsfield.
Needs to be more like 30c -32c.
Putting him/her outside is the best thing you could do for your tortoise. Being aware of birds etc is fine, but stopping your tortoise from being outside because of this is not.
I have kept tortoises for over 36yrs and never had a tortoise gone because of birds. I have had one tortoise escape from their enclosure, but my garden is secure from my torts escaping, so it was just a matter of finding them. Birds, foxes etc are to make you aware of their problem, but using common sense you can over come these problems.
Your tortoise has become a picky tortoise, just like us they prefer junk foods (lettuce, tomatoes, cucumber etc) if your tortoise has good food to eat, then his will is stronger than yours:0) They know you will feed the foods he wants if he holds out long enough:0) If the good foods are there they will not starve, as they will eat when they are hungry.
It took me three months once to get a tortoise I rehomed to get to eat good foods. Its not easy, but its possible. You have to be stronger minded than your tortoise:0)