Have you done much to it besides setting up Evolution?
(which I regard as an odd choice, given that Thunderbird is now the default distribution email client - I’ve had it working reasonably well with Exchange servers. I confess I gave up on Evolution as being horribly clunky ages ago).
As a user of Ubuntu for my daily workload for over 10 years I’ll be interested to see what tweaks you’ve made.
Thoroughly concur with your assessment of the economics of the EWA, as you know - the NHS was spending about 9 figures on it (or so I heard). A mere 5% of that distributed to open-source projects would net you a LOT more control over what you got for your money - even a customer as large as the NHS is not terribly influential to a behemoth like Microsoft.
I suspect the reason Microsoft decided it was no longer a good idea was because such a large budget line-item looks ripe for reduction and NHSbuntu is a very logical way to do that.
Caveats : the sheer number of horrible VBA applications around the place cannot be underestimated. An ecosystem of consultancy services devoted to converting these to LibreOffice macros (or better application platforms, where applicable) is probably required for this kind of sea change to take place. Likewise training on OSS applications, etc.
Horrors based on Sharepoint are probably also a speedbump here. This, of course, is the reason Microsoft promotes the creation of horrors based on Sharepoint so enthusiastically.