Will vary between unis but generally STEM courses including engineering have more contact hours on average. Generally though you have more contact hours in the earlier years of the course than the later years. I would probably anticipate 20-25 contact hours a week for a first year engineering course most likely, including labs and tutorials etc.
It's generally not advisable to work more than 15 hours a week max if you're a full time student on any course, and even that is impractical for most. I would probably suggest 8-12 hours a week realistically for most.
Bear in mind also it's very likely your timetable will change each term so finding a job which allows you to work flexibly enough to have your hours change every 3 months can be challenging, unless you are purely working after 5pm every day (in which case you need to balance that so you don't burn out by being over tired constantly), or only on the weekends (in which case you need to be sure you allocate sufficient time in the week for all your assignments etc.
If you're very keen on working while studying then particularly for engineering (civil or otherwise) it's worth looking into degree apprenticeships, as there are quite a few available including at notable engineering firms (and the much greater amount of work experience you have will make you a lot more employable at the end, assuming you don't just remain with the company that you did the apprenticeship with in the first place).