Have a look at quickiedivorce.com
There’s quite a few like it and they have all the guides and works out cheap, but to be honest it’s almost as easy to go to the office where you hand in the paperwork and they’ve got all the forms and guides for you. Relatively easy to do but there are only 4(?) ways of doing it – 2 years separation and both sign, 5 years separation and only 1 signs, adultery or irreconcilable differences. The people at the council offices are usually very helpful.
Good luck. I did it with my ex-wife all very amicably as she’d changed her mind on wanting kids. I’m now super happy with a 6 month old boy and a fantastic partner (I hate that phrase but girlfriend sounds too glib).