Must admit, I'm kind of in a very similar situation...
Up to around this time last year, I'd not been in a band for about 5 years (and then I was playing guitar). Saw an ad locally looking for a bass player and they mentioned not only were they planning on doing originals, but were also a bunch of forty-somethings. Got in touch, started something up and were getting on great until one guitarist got a new job & had to relocate. Band disintegrated.
I advertised again, got a couple of approaches for covers bands, so went along not knowing how to play the songs fully, apologised in advance & then quickly went through the songs with the guitarist and followed him & the drummer. Wasn't perfect, but must have done something right, as they asked me to join the band at the end of the rehearsal!
Anyway, I've now ended up getting something going with the other guitarist from the first band.
Covers? Learn the basics of the song & interact with the guitars / drums / keys / vocals as you would in any other band situation.
And good luck, hope something suitable comes your way!