It isn't too difficult to do the actual divorce bit yourself if you are prepared to do some research and form filling. Finances are trickier and unless they happen to be a family lawyer most people will require a family solicitor to at least draft a consent order documenting any financial agreement in a way the courts can ratify.
If the value of any assets is substantial or the finances are complicated a high street solicitor will give you a more personal service. Online services are cheaper but you don't get the same level of service.
When you come to specific questions, the legal board (under 'other stuff') has some really good family solicitors that post on there. If you're both amicable then there's really no reason you can't do it yourself. DWP has good really basic information https://www.gov.uk/divorce/overview
First thing one of you has to do is petition for a divorce - all the links for forms are on that website.
Also wikivorce is a site specifically set up for people trying to divorce without a solicitor.
The financials are treated completely separately from the divorce. There's lots of guidance out there on what's deemed to be fair, no reason you can't decide yourselves how to split things up. Then you'll need to get it drawn up into a consent order, which will then need to be stamped by the court to make it legally binding. Don't think they accept the consent order unless it's been drafted by a solicitor, but shouldn't cost much if you've agreed the details yourselves.