Will you come and visit me in hospital when I have my operation?
We don't use an article before certain nouns (places) when we talk about being at the place for its 'normal purpose'.
These include many everyday places, incuding
in bed
in/at church
in class
at/in college
in court
at home
in hospital (British English; Americans say 'in the hospital')
in prison
in/at school
at sea (Compare "on board" a ship, train, aircraft, etc)
in town
at university (British English, but 'at the university' is also used in BrE, and is the norm for American English)
at work
If you go to one of these places 'as a participant' you also leave out the article. But we don't *'go to home' in standard English. And 'go to town' also means, informallly, 'perform or do thoroughly, etc.'
I adapted a list found in Oxford guide to english grammar (1994, 2002) by John Eastwood. Regarding university the author writes:
university
(studying) at university, go to university (to study); But at/to the university is also possible and is normal in the USA.