The term "personally expressive photography" is used fairly commonly among "fine art" photographers. By "fine art" I'm not referring to over processed Hallmark greeting card shots, nor am I referring to popular urban ruin photography, or portraits with fake backlighting.
I'd suggest you read Guy Tal's books. I enjoyed Another Day Not Wasted a lot. He also writes a regular column for Lenswork magazine which I encourage you to check out.
Are you a subscriber to Adobe Creative Cloud? If so, the Behance website is part of the deal. There is also Adobe Portfolio. For a portfolio these two should suffice. I've used Smugmug for 15 years and Zenfolio for 7 years, but I prefer Behance for portfolio work.
Competitions I don't recommend when I teach my class about this stuff. They are usually a rights grab at a minimum. Consider submitting images for juried exhibitions. You make better connections that way.
Well just about all larger international and national photo competitions won't be able to offer any serious critique due to volume of entries.
Which particular events are you considering?
My advice would be to participate in smaller juried exhibitions in nearby venues or cities. In the US, the CAFE website lists these; maybe there is a UK version you can check out.
Just research customer reviews on reseller ratings and BBB. Their sales staff will call you to upsell prior to approving the credit card charges.
Plus they’re in Brooklyn not Maine.
Darktable is the only accurate LR Classic alternative. The other two only offer Develop capabilities.
You need to understand your requirements in post processing software and which tools should be considered. LR Classic has a serious image management database that is more special than the development capabilities. The latter, while powerful in LRC, can be matched more or less by RawTherapee and other image processing tools. LRC also offers a good, not great, printing capability, book making, a useful mapping, strong integration with Photoshop, and the full Adobe Creative Cloud bucket of apps, which can be highly valuable if you need a no-additional-cost web presence.
I shot youth sports for many years. Venues included indoor soccer arenas which are basically warehouses, small school lacrosse and soccer fields that have lousy non-LED lighting, and gyms. To freeze action that fills the frame, even at f2.8 in a long lens, requires a shutter speed of 1/1000, though I preferred 1/1500. To achieve that, ISO 12800 was necessary.
With newer cameras I could see using ISO 25600 if necessary. These days sensors can handle it well enough, and the newer NR apps like Topaz Denoise AI work really well. Sports is not fine art so there's enough quality wiggle room.
Other than sports and events, I tend to keep things around ISO 100-400.
Get a couple of rechargeable hand warmers. I have two in my camera bag. Wonderful invention!