In Maryland, legally at least one parent must be the primary educator to be considered homeschooling. But, no one else should be instructing your child daily for the majority of his lessons. (Co-ops are described below.) If you might meet someone who offers to "homeschool" your children for a fee, that is an illegal school in MD. And, if you have a high schooler, you will want to be in compliance so that when it comes time for transcripts, etc., you can produce the documents he will need to further his career goals. As for teaching support systems, there are several venues open to high schoolers: there are courses offered at community colleges and co-ops. A co-op is a group of families who meet either once or twice per week to teach their students together a select group of subjects. There are at least two core subjects that are not included in that co-op. Some co-ops are virtual (computer-based) and some meet at churches. But, if you continue to work full-time in the daytime and your husband works, you might not be able to participate. Co-ops meet during school hours and some require parents to teach at least one class or serve as a volunteer. A tutorial is a program that hires professional educators to teach several specialty subjects; however, again, they do not teach all subjects. Most will leave either math or grammar to you. Anything structured differently is a school. Yes, there are computer-based programs, but then your child misses out on positive peer interaction/human interaction. High schoolers also have hours that must be counted to equal an actual credit. Anyway, I wouldn't advise the computer as my sole homeschool method for either a preschooler nor for a teen in the first year. There are also emotional/spiritual support systems and resources, which I can offer offline if you need them.
As for whether or not you can work and homeschool--Yes, You Can! Well, at least after you consider some things. What type of career do you have? Is there enough flexibility built in or is it deadline oriented? Frequent meetings? Travel? It can be done, but it's not comfortable. You have to plan for the chaos that could ensue no matter the choice you make. If you homeschool your 4-year-old and not your older child, you still have obligations to the PTA, your job, and your family, now ALL while you have to spend the time teaching your preschooler. You will still have to do lesson plans and take on the role of an entire school!? It can be done, but do so with eyes wide open.
The first year is the hardest for so many reasons. But, once you get into a rhythm, you wonder why you didn't choose home education sooner. As for pulling out your teen, I have heard of people who begin homeschooling with teens, and it's hard. You need a period to adjust as a family, and depending on your teen's grade level, you lose that relaxation when you know you soon have to prepare for SAT, prom, higher level courses & recordkeeping, transcripts, etc. This is my opinion.
How to sell this to your husband? There is a convention at the Dulles Expo Center on July 10 and 11. Google NOVA Homeschool Convention. Maybe you could take your husband, though the conventions tend to be a bit overwhelming. There are workshops and vendors who offer discounts, but I wouldn't buy anything at that time. You can find more resources with deeper discounts used online. If you want to learn more about home education in MD, a workshop is scheduled for Saturday, July 25, 11 am-1 pm, at the Accokeek Library. Pick up a flier. Hear from a county representative some of the rules and challenges in homeschooling. There are tons of books out there, and again, the co-ops. If you decide to homeschool, send an email to me offline and I'll send you links to Web sites and more resources.
Meanwhile, as you research home education, be realistic. Present the pros and cons to your husband. Finances, time management, and socialization are real challenges of life anyway. You'll need your husband's buy-in, because if he's not onboard, it's double the challenge. Schools have substitute teachers. You might not for a while. Add to that your full-time job requirements and deadlines, and it gets really complicated.
I advocate home education, but I'm not against institutionalized instruction. Research private school for your preschooler. Some offer scholarships. If you still want to homeschool, don't be surprised if your teen thinks you've lost your mind and resists, especially if he had dreams of avoiding homework, sleeping late, eating and watching TV and video games all day. My son was shocked when he found homeschool to be harder because he couldn't hide behind any of his classmates and had to really pay attention and answer questions. LOL