General rule about the venue: very often, you can get a space for free. Your targets are: big coworking spaces, hackerspaces, makerspaces, universities, local companies, and startups. These are the places that may be willing to offer you space for free (especially during evenings).
The setup should allow you to sit everyone comfortably in small groups. The best setup is just square tables (or two tables put together) with 4 chairs around them. An excellent venue will have a few side rooms where you can run specific workshops or tutorials away from the main group.
It's also worth checking that your venue has public liability insurance to cover events held in the space.
Power cords Edit
Most CodeUp sessions run for just two hours, so not everyone will need power, but it's good to have plenty of available sockets just in case. Often the venue can offer you extension cords if required.
Internet is crucial, so ask your venue provider if they have tested the WiFi before. You need to ensure it can handle the number of attendees you're expecting, and be easy to logon to.
It is possible that the venue will claim they can handle Internet traffic, but during the workshop it turns out they can't. It's a good idea to ask if they have previously hosted programming workshops for 30+ people.
If you're branch is sponsored, the CodeUp organisation can provide you with banner stands and posters to decorate the space with. Just contact us for more information.