i wouldn't recommend using the Royal Mail service
several times a week i get a big bundle of flyers/leaflets pushed through the door with my important mail
it invariably goes straight through the shredder and onto the compost heap
try and look for a solus service - but if you think about it, you can probably deliver 100 per hour on foot. (big posh houses with long drives will reduce that number, blocks of flats will increase that number)
minimum wage is £5.8 or so an hour, so if you see services at under £58 per thousand, you have to wonder if they'll actually be getting delivered
Of course, i'd be interested to hear how companies CAN do it for less that that sort of rate. I don't wish to imply that they are conning you or providing a poor service.
Just intersted in how it's done.