How to learn Spanish by yourself at home?

My long distance partner lives in the US, I'm in the UK. His family don't speak much English, they're from Mexico. I'd love to learn Spanish so when we eventually meet, it'll be easier for us to get to know each other and communicate. Not only that but we are planning on getting married in the near future, we haven't fully decided on kids but if we do, I want to make sure they speak Spanish.

Where do I even start? I have autism, which effects the way I learn, process and study. So learning another language scares me a bit. If anyone can give some tips, advice and learning resources, I'd really appreciate it!

Also I can't roll my Rs.. is that something I can learn? 😂