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Depending on what exactly you want to do in Germany, you might need a residence and work permit. Otherwise, you would apply for a C Schengen visa for the first visit and mention that more will follow.
Summarized, a C visa allows you to come to Germany and talk about work, you need a work permit to come to Germany and do work.
Usually first-time Schengen visa are single-entry visa with a duration for just one trip. After several applications without incidents like overstay, they give longer multi-entry visa. For an UK resident with a stable job, it would be relatively likely to get a multi-entry visa soon.
For residence permits, ask on Expatriates Stack Exchange.