If you are making decisions in the dark, about an environment you hardly know, the best solution is to be as flexible as possible.
Buy an amp and separate cab.
Watts are cheap. Too many is never a problem, but too few will always ruin the gig. If you think you want 100 watts, get 200, even 300 watts because you will sound pretty bad if you buy a 100 watt amp and find you need to use 100 watts. You need clean headroom for the best bass sound, so you will sound much better using 100 watts from a 300 watt amp. I used to play in a duo with a miked up acoustic guitarist. I used a 500 watt amp and a good 112. IME a 500 watt amp with the volume on 3 sounds much better than a 100 watt amp with the volume on 9.
It looks to me like you are totally underestimating your requirements. If I'm wrong, that's great, but if I'm right you won't sound good on gigs and will be trying to buy a larger rig in no time. A small low powered combo could be an expensive mistake. An amp and cab enables you to replace/upgrade each separately. Lets you add another cab or use a different cab.