What are my options for applying for a new ED visa in Thailand after returning on a 30-day exemption?

Swedish passport holder. Currently on an ED visa (language school) that expires 27th October. Planning to apply to study at Ramkamhaeng University, admissions are November 2-5, the term begins November 7.

I want to go back to visit Sweden before school starts. My plan is to come back late October on a 30-day exemption, apply for school and then apply for an ED visa. The program I'm planning to study is a program for Thai students, not an international program, and the school says they will not help me to apply for my visa. They will only provide me with a document that certifies that I am enrolled in a program which I am to present to immigration.

I'm looking for insight on how I will apply for my new ED visa once I get back on a 30-day exemption. If I will need to leave the country to do so. I also want to know if I am making any mistakes such as by coming back on a 30-day exemption but as far as I can see that is my only option. I would prefer to apply for a visa in Sweden but obviously I need to be enrolled before I can do that, and my current visa expires before I'll have a chance to be enrolled. I doubt they would grant me an extension of stay based on having plans of applying to school?

So I'm wondering if anyone has some critique or insight to offer to help me plan things out a bit better. I would be open to using an agent to help me sort things out so if you have specific recommendations please feel free to send me a PM.

For additional information, my history is littered with tourist visas and most recently 9 + 6 months of ED visas for language school studies. Never had any problems before but I expect to get questioned trying to enter on a 30-day exemption with my history. Even if I do get questioned I feel fairly confident I'll be able to get through it but I'd rather avoid it altogether if there's a way.

Thanks in advance for any advice.