What (if any) products do you currently use?
I would keep it simple and use a daily sunscreen to protect your skin from more damage, and then use a retinol product. I use La Roche Posay SPF 50+, it's usually on sale in Boots, or they do 3 for 2.
There are some good mid range brands like The Ordinary and Geek and Gorgeous. The problem is they have so many products it's hard to know where to start and can get a bit overwhelming. Unfortunately you wont find Geek & Gorgeous in shops, you have to buy it from their website, but their prices are good, I've been buying from them for a few years.
I actually use the prescription tretinoin stuff now, which you could try if you wanted - there are many threads on here about Dermatica or Skin & Me. It depends on how much time/effort/ money you want to commit to. They are subscription services that send out the prescription strength stuff - but be warned it can be very irritating, so I would recommend starting out using over the counter stuff like retinol/ retinal.
I started out using the Ordinary retinol and then Geek and Gorgeous retinal cream and then built up over time to using stronger stuff.
You could try using it maybe a couple of nights a week to start with and building up use:
https://geekgorgeous.co.uk/products/a-game-5
They also have a stronger one you could work up to. Just be aware it has a yellowish tint to it, so I would put it on a good while before bed to let it absorb in or you will find yellow marks on your pillow.
The Ordinary also do lots of retinols that are pretty cheap, you can get them in Boots - they are great to start off with. Just pick one and start using it a few nights a week on a clean face. Here is a link to their Retinal serum (which is slightly stronger than retinol - I know, very confusing)
https://www.boots.com/the-ordinary-retinal-0-2-emulsion-serum-15ml-10340633
If you get irritation then use it less often, and try building up slowly to using it every night/ every other night. It should start to smooth out your skin and give it a little more bounce - bit it takes time unfortunately.
Just make sure if you're using any retinol product that you use sunscreen everyday.
Also (sorry for the essay), if you want to try a Vitamin C serum in the morning under your sunscreen.
Again Geek and Gorgeous do a reasonably priced one called C-Glow. I find it makes me skin glow when I use it.
https://geekgorgeous.co.uk/products/c-glow