How to book tatkal tickets for 1A class from Mumbai to Surat with luggage

Guys yesterday I posted a thread asking for taxi from Mumbai to Surat and you guys have been helpful to not do that because of road conditions. I get it. But, I looked for train tickets and there’s a waiting list in all of them. Some guys suggested try tatkal but I have no idea what that is and how does it work. Also, is it convenient travelling in train if I have two check in bags, one cabin bag and one backpack? Like I can get a coolie for sure from taxi drop off to platform but what about going inside the berth. Also, what about departing the train at Surat. I am imagining the different scenarios and I don’t know what can go wrong. Also, does the trains have wifi? Should I stick to longer, inconvenient but straightforward route which is taxi? Or I am just being little extra imagining all these. I used to be huge train travel guy back in the days (10 years ago) but it was all general coach adventures. To give you more information, I am 29M lol. And, I would not have a sim card with me. There’s no direct flights as well. The ones are via Hyderabad and all for 8 hours or so. Looks like I fucked up by not booking a train tickets in advance? I would be looking for trains after 9 AM just to be safe.