I've been looking at this as well, maybe worth using a referencing agency? Can get a basic check done for ~£15.
Or at least things like find where they (say they) work and check to make they do actually work there (with their permission obviously).
To be honest, with a lodger, you're going to be living with the person, so as well as making sure they're going to pay the rent on time and not trash the place, it's important to make sure you get on with them a bit and don't completely hate their guts!
A set of house rules (that you
both stick to) agreed up front is probably also a good idea, gives you both an idea of what is expected.
As a live-in landlord, you do however have the benefit that there's no legally defined notice period - it just has to be "reasonable". So whilst under normal circumstances 2-4 weeks would probably been seen as reasonable, if you come home to find that they've trashed the place, you'd be perfectly OK to kick them out within a day or 2.