Okay OP I was here last year. I went to a wedding and I spent the days in the run up to said wedding in floods of tears feeling shit about the way I look and felt like I would stick out like a sore thumb as not fitting in with the well groomed people that would be there. Today I feel confident, and yes, hot! (never thought I'd say that but here we are). I still get days where I feel shite BUT for the most part I feel good (or at least better) about myself. Here is what I did ...
So, after the wedding I vowed to myself I would make small changes daily. I told myself that this is the worst I will ever look because from now on I will make an effort to be the best version of myself I can be within my capability and budget (I'm also poor btw).
Day after the wedding I threw out almost all of my scruffy/stained clothing (kept some for painting/gardening). I have spent months scouring the charity shops for nice clothes and my wardrobe has built up nicely.
I made very, very small changes to start. I never wore make up (still don't for the most part) but I wear mascara every day now. Make sure my nails aren't chipped (I won't pay to have them done). I wear earrings and other jewellery daily. I stopped keeping certain items 'for best'.
Later last year I had my 40th birthday, next day (Christmas day) I got with my now partner (he's 29 😬) - we did have a split where I ended up with a 26 year old but now we're back together (it sounds like a shit show and it probably is but never had more fun in my life).
I considered what my best 'asset', visually, is. Probably my legs, now before I would NEVER wear skirts. I now live in them. Have a look at what is trending fashion wise and try to emulate that on a budget, I tend to dress in a more classic/old money style and often find VERY reasonably priced items that fit the bill in the charity shops.
I spend next to nothing on beauty products. Most moisturisers etc will do the same as the next so don't be suckered into buying expensive products promising to make you look twenty years younger.
Finally, mindset. I hate to say it but we're not getting younger, so make the most of what you have to offer now. Make the most of how you look NOW. If you don't you will look back one day and think "fuck, I was trying to be hot and I WAS hot, now I'm not". The biggest thing holding you back from believing it is you. Confidence is a case of fake it until you make it. I'm not the best looking woman who will walk into the pub BUT I'm 'hot' enough, I have a great sense of humour, a wicked laugh and know how to let myself go and that has been enough for me to attract plenty of men. Trust me, act like you're the hottest thing in the world, you ARE the main character in your own life so live like that.
Good luck OP, rooting for you! You have absolutely got this!