There are two sorts of pages at the moment available to you:
A Google+ Page which appears for a search and which is driven by a selection of data from the Places entry.
In the case you posit:
We are in the UK, we have lots of clients that are 'local' in that they have an office/workshop/whatever and hence generate business locally. BUT, they have business that is generated nationwide across the UK.
The Business Guidelines for a Places entry say you can only have one Places entry at the office or unit location.
In the case of a multi-national which has local shops, offices or service units then they can have a Places entry for the main office if they wish and its in the guidelines for walk in visitors and then one for each location which is open and staffed for the stated hours. If the locations are a service depot, like British Gas say, then they have to be set up as a Service Area business.
Then there are the new + social pages:
Note you can use the same name in several +Profiles as appropriate:
Personal
Business
Hobby or Social Club
But only post content as appropriate
A +Profile which has to be in an individuals name
A +Brand page which has to be under a +Profile where your blogger(s) or networking professional(s) can promote the brand. This should not post links to +Local Business pages to avoid spam take downs.
A +Local Business page for a location which has to be under a +Profile page, but this can be the local manager as a place holder.
In the case you posit this could be possible:
A +Profile or a +Brand page could be used to promote the business nationally.
As far as I know this is not prohibited:
You can set a +Profile up for a local manager and then set up a +Local Business page below it without having any local Places entry.
The manager can post from the +Local Business page information relevant to his local area and customers.
He can encourage customers to Circle the page from their +Profile if individuals or Follow it if they are businesses. And once they have done that you can Follow them back. A +Local Business page cannot Circle others like a +Profile so it cannot 'network'.
As part of Googles ham fisted dash to mobile phone waving socialites, the +social stuff is really aimed at drinkeries, eateries and enjoyeries which someone out on the town is likely to search for from their web enabled phone or tablet. Most Yell mobile searches are for eateries.
Obviously for social oriented businesses having a cohort of old customers commenting on your Posts and interacting with potential customers who have Circled/Followed the page is supposed to increase your business.
For real businesses like carpenters, electricians and plumbers I would think the time to embrace 'social' would not be a good return on investment.
Now there is the Communities option which may work for skill based activities where advising DIYers may garner business from the less dextrous, physically or mentally, based on your insightful comments.
I have set up in the UK:
Birmingham Blogs
Birmingham Websites
Birmingham Google+
having read a post by Linda here to see if that would work for me and my website guy. One join so far. Its a new feature so get in early and give it a go.
Some social engagement in the +world for all businesses is probably advisable for +es and reviews from users already with a +Profile.
But its probably like blogging, posting just once a month will not gain much traction.