About to sign a lease for an apartment in Edinburgh... Is this a red flag?

Hi, so I'm a student at UoE and I really need a place to stay. I found this listing on Gumtree, seriously close to the university, 2 bedrooms, £800 a month and deposit is £800. I'm thinking of renting this place for a year with a buddy of mine, splitting the rent.

I've seen the place myself, met the guy personally, and the lease document is apparently done. But because I've never done this kind of things before, looking up a bunch of things leaves me a bit worried:

• He says that when signing the lease we should pay at least some part of the deposit - in cash. Of course I'm not going to pay the full amount immediately, but could it be a sign of a scam?

• There are no tenants living in the flat at the moment, so I couldn't ask anyone about the landlord.

• He hasn't asked me anything regarding guarantors, or credit checks, all he said is that I need an ID when signing? How exactly do credit checks work?

I have his number, and I can ask him any questions. The lease starts from June so I still have time. What should I do?

EDIT: Thanks for the advice, I think I'll pass this offer and look for something else.