However, a couple of points:
* The £1/site/month is too low. I won't trust you to be able to rent and manage a network of decent machines for that price point, so I wouldn't trust your results. You're also going to eat costs trying to support cheap one-site-owners. Try a price point like "£5 for 5 sites a month!" so that even if you have one site, you pay at least £5 a month.
* Show me your (hopefully) geographically dispersed network. Like a map showing where your machines are with fancy lines and all that. I want to know you know what you're doing and at the very least you should have a network of independent machines, geographically spread. Tell me you're using independent datacenters/cloud hosting for maximum availability.
* I don't know the current state of Go, but as a potential customer I'm questioning the logic of using an experimental language (as I see it) for an uptime monitoring system. Presumably you want to have the highest uptime as possible, and maybe Go interpreters/compilers have bugs that will affect you. I would not advertise the fact you're using Go.
* Link me to a dashboard where I can see the statusses of your service, and any maintenance messages you might have had. This might strike you as odd, but I would trust you more if you had a public page where you can show past incidents and how you resolved them, or at least a table full of green lights showing all your stuff is up. Some things can fail (without losing uptime), and I'd like to see you being open about it.
I understand you're just beginning so cherry pick from this comment what you like :) Either way it's a nice looking landing page.