Hi there, Jo-Anne! I also have a 3 and 6 year old! There are lots of activities available to keep you and your kids busy. We joined MOMS Club several years ago and that has been wonderful. My chapter has lots of field trips, crafts, park days, parties, and stuff like that for younger kids (although my 6 year old is always welcome too).
On your own, you can sign up for classes at the Rio Grande Nature Center, Explora, Zoo/Aquarium classes, Natural History Museum classes, Saturday art classes at the ABQ Museum or music classes at UNM, etc. These are often after-school activities so your kids wouldn't necessarily be with homeschoolers. The Erna Fergussen library has some art activities as well, you could give them a call.
Geared specifically to homeschoolers, you might consider (if you haven't already) joining a support group, because then you also have the possibility of going to classes (often less expensive) at some of the above places at a group rate. For example, our co-op has a gymnastics class, a Spanish class starting up in January, we're consideringa yoga class, etc. Most support groups also band together to do fieldtrips, have holiday parties, and so onl.
There are SO MANY things going on that I've only touched on a few things. Take a look at the free NM Kids magazine (pick it up at most libraries) to get some more ideas.