New to torts

[emma_mcraf]

Hi everyone. I've kind of been thrown in at the deep end as I've been asked to take in a Hermann male tortoise as an eldery family friend has suffered a stroke and is unable to care for it anymore. He was given it as a gift from another elderly lady and has only had it for a few years. I have no idea how old the tortoise is. I've always wanted one and am delighted that he has entrusted my family with it as he knows we'll love and care for it. We've decided to call him Theo!
We are collecting Theo on Thursday (2 days time) and are desperately hoping to put together his enclosures before then. I've spent all the day researching online and found many sites recommend completely different things for Hermanns. I've concluded that he'll need an outside enclosure with solid walls, substrate made from a mixture of topsoil and playsand, around a 50:50 mix, with a covered area, different gradients and a few pebbles, rocks, sunken water tray, etc. Again, the same for an indoor enclosure but with a UVB lamp and basking lamp. Is that right???
My query is that we'll have a mesh lid on the outside enclosure to keep predators away but what happens if it rains? Do we need to have another cover to keep the substrate dry too?
I've researched Theo's diet and I see Dandelions, honeysuckle flowers, clover, etc ard fine with occassional teeny bits of certain fruit and a cuttlefish for calcium. Should I also get D3 supplements from the pet shop?
If anyone else can recommend anything else I need to get or correct me on anything I've mentioned, your comments would be greatly appreciated.
Thanks x