Hi Reini
If you are at Sheffield Uni have you have the ELTC activities and the One World Cafe opportunities
Voluntary activities as Bludragonfly suggested are also useful
It's getting towards the time of year when academic departments often become quite sociable with staff get-togethers/parties so try to maximise these opportunities and be open with people in terms of you wanting to practice your speaking skills.
Also if there are specific groups of people within your department who you need to communicate with regularly take this 'festive' time of year to suggest taking a tea or coffee break - offer them a biscuit or some cake and you may be able to extend the conversation time.