It's worthwhile having a look at the
NRLA website.
There is information on there on what you need to do as a Landlord - much more if you join including training courses.
Agents are useful to find tenants and do the necessary checks, set up the AST etc. Expect them to take around 15% + VAT. Make sure you have contract with them that allows you to end the contract with them after a period
Without Charge - say 12 months by which time you should have some experience. If the agents won't or don't allow that walk away - there are plenty around.
An Assured Shorterm Tenancy lasts for 6 months minimum unless contracted longer, after which it roll over into a 'Periodic Tenancy'. To end the tenancy after the AST period you have to give 2 months notice, the tenant 1 month.
Your first 'homework' is read the doc's found
here.
Your next 'homework' is get the following paperwork together for Energy Performance (EPC) (10 years), EICR (5 Years), LL Gas Certificate (Annual), the how to rent document all to give to the tenant. You need a list of maintenance people to do emergency repairs for you - if you use an agent and you don't have a list of your preferred maintainers then they will use their suppliers at the agents charge - expensive.
Important items in the AST (I recommend you read and use the NRLA model AST as a guide at the very least) is to include a paragraph on Rent increases (5% or RPI which ever is the greater), annually; you don't have to have a rent increase every year but without the clause it's more paperwork to get one, I'd recommend that you always have an annual rent increase - I know - I let the agent not increase the rent, it's now 'costing' me £150 a month! There is no need to have a new AST every year unless you have new tenants (I've had the same tenants for 15 years without a new AST). The AST should say who is responsible for certain repairs e.g glass, waste disposal, garden maintenance.
You have to supply certain items - Cooker, Vacuum Cleaner, Lawn mower all spring to mind.
Before you let the property (either direct or via an agent) Take lots of 'photo's, record serial numbers items supplied. Prepare and have to hand to pass on to tenants simple instruction sheets on how operate door locks, window locks, Alarm (including user code but not how to change it or engineer code), central heating, supplied items.
Prepare a duplicated document with the photo's on, on the day the tenant moves in walk the tenants around the property with that document and get them to initial your copy of the document that they agree with the image and condition of the item.
Edit - see next posting
There is a lot more I could say but for now - the NRLA is your real friend!