Considering how much time has passed since you have left, I think your possibilities are going to be strained if you want to go to the UK next month. To be honest, it will be a bit enthusiastic to think you will be returning next month and actually allowed into the UK without a visa in hand. Your ILR has thoroughly lapsed.
There is the Returning Resident application, but the problems with this are:
- It is notoriously difficult, if not impossible, to get this visa. I've only seen one success story myself, and that was after an appeal of the initial refusal with a very good lawyer (and maybe a bit of luck and a judge who was in a liberal mood that day).
- It takes time to get this visa, easily weeks to months before a decision is reached, not to mention the time it takes to prepare the application and send it off. If it is not successful, which it most likely will not be, you will again be at square one unless you make an appeal that is likely to fail anyway.
You can apply for the Spouse Visa. Your husband has to provide certain minimum evidence of his ability to support you (son is excluded as he is BC) including meeting certain minimum financial qualifications. I'm assuming he qualifies, although concerned about the time he may have worked with his current employer as some minimum pay details require evidence. He may have a big fat bank account however, so won't go further into that. Therefore, your big issue again is just time. This visa is quicker and many cases have been sorted out in weeks (website says usually within 12 weeks), but it can take longer, even for 'straightforward' applications. Apply now, be ready to wait that full 12 weeks, and wait and wait....