If you are planning to do a collaborative research project for your dissertation, or for part of it, and this involves human subjects and personal data, you must know about research ethics, research registration, and data protection. There are important changes to data protection, the General Data Protection Regulation, also known as GDPR.
UCL has lots of guidance on this. Look at the links to begin to familiarise yourself. You will also receive information during your master's course if primary data collection is encouraged. Primary data collection is when new data are collected as opposed to secondary data, which are data that already exist for another purpose but are available for further analyses e.g. survey data (with appropriate approvals!). Not all master's courses support new data being collected from human subjects because it is very hard to get through the research ethics process in time. You must check with your personal tutor or supervisor about this.
It is important to remember that collaborating with someone is not the same as someone being the 'subject' of your research or a participant in your research. If you collect information (data) from anyone for the purposes of research, they are a research participant and research ethics applies. Collaborating with someone is about being at the same level and both inputting to the research as a researcher. Ethics is not needed for this.
Service evaluation is different and involves considering an existing service - no additional information is collected. Service evaluation does not require research ethics approvals. However, service evaluations alone are unlikely to be sufficient for your postgraduate-level dissertation. You would need to speak to your supervisor about this.