My daughter is in a similar situation - she was in a good pre-k program when she was 3. But my husband's job moved him to a place where there are NO decent pre-k programs, so we had to take it upon ourselves. I chose to forego the online and formal curricula and teach her what I thought she needed to know. We started with Dr Seuss's ABC book (this was actually before she ever started pre-k, but I'm not sure where your dd is, so I'll start from the beginning.) When she could identify letters, we started working on sounds. Then (this was the slow, excruciating part) sounding out words. She read "Hop on Pop" by herself when she had just turned 4. I spend about ten minutes a day having her read to me - at her age, I don't think she has the attention span for more than that. Then I let her choose a book at I read to her as a reward.
I started teaching her basic math concepts as well - first counting, then writing numbers, adding and subtracting, just a little at a time (maybe 4-5 problems a day until she started to enjoy it, then increased it a bit.) I got math workbooks from Target, but you can also google "addition worksheets" or something similar and find a ton of free stuff to print out.
Over the past couple of months, I've started her on a journal. She writes stories in it - mostly simple ones, but it takes a while for her to do it because at this point I have to spell almost every word for her and she often has to erase the letters and rewrite them. This helps with her handwriting and lets her start getting the basics of grammar and punctuation.
Then as a bonus, I add things that are not necessarily fundamental, but that interest her. I bought a couple of books about animals, and we read a few pages of that every day and we talk about it. I wasn't sure if she was getting anything out of it, but she occasionally pops up with odd facts that show me she is. (Like when we saw a deer in the road, and she said, "That's a FEMALE deer - it's a girl. Because it doesn't have antlers.") I also printed out a US Map, and she's learning one state at a time. When she can identify the state if I point to it, she gets to color it. She knows 38 states now, and is working on the rest.
This might not work for everyone - but it has worked pretty well for my DD. It's a lot of work, but she enjoys it and is learning a lot. Hope I helped!
