As I am working on contract in Leeds I only want to committ myself to 3 months rent, then 1 month notice ie 4 months minimum.

The LA (who works from home) says thats ok with landlord.

He also wants 2 months up front rather than pay a deposit.

There's plenty for rent in Leeds but most are 6 months AST

I'm getting an uneasy feeling. What should I be wary of?

Any advice is welcome.

If the landlord is willing, you could sign up for a 3 month AST, then go onto a rolling month-to-month statutory periodic tenancy.

However, the LL will be carrying quite a bit of risk. He will not be able to serve an S.21 to regain possession earlier than 6 months, so he has no comeback if he wanted you to leave at the end of the shorter fixed term and you continued to pay rent. 2 months' rent up front leaves the LL with still less protection (IMHO), because if you were to pay no further rent, he wouldn't find out until 2 months into the tenancy, by which point S.8 repossession proceedings would probably take you past the 4 month mark. But he's probably attempting to avoid the TDS, and that's his choice.

Read the terms and conditions carefully, making sure you're not signing up to a fixed term longer than you require, and make absolutely sure the LL and LA are in agreement -- but I see nothing else to worry about from your point of view.