Hi, OP -
You may have heard of retinol/retinal. They are precursors of tretinoin, which is a prescription retinoid. There are others. Adapalene is milder and cheaper and available without a prescription in the US. It is a good starter. I will return to tret below.
Another good one is the newest, trifarotene, which Boots OnLine will prescribe. (The service is free) It is about £55-60 but that’s for 75g, a large amount that will last for several months minimum. They also do adapalene very reasonably. I started with their adapalene and worked up to trifarotene. I also use Face Theory Azaleic Acid for soothing, anti redness and mild exfoliation. I am very happy with the results from about two years of mild cleansing, morning sun cream/night time treatment and lots of moisture always. Much more effective than the toners, multiple serums and creams I was using before, and less expensive. It’s been good for my mild rosacea, great for my skin texture and pores and very good for my sun damage (I grew up in a Mediterranean climate scorning sun cream and I am older than you, and moderately fair). I didn’t have many very deep wrinkles and I haven’t kept photos but I think they are softening, also.
But tretinoin is the gold standard. Unfortunately unless you have significant acne the only way to get within the UK is through a subscription service: Monderma, Uncouth, Skin and Me and Dermatica seem to be the main ones, also the very upmarket Klira. These services will compound your tret with some other ingredients for, I think, £25-30 pcm for 15g, which you can cancel or stretch out. (Except for Klira) Many on here really rate them! There are bargains, too - some will share their codes to give you a month almost for free.
Also pure tret can be imported from various online sources cheap as chips. Many rate online pharmacies Skinorac and All Day Chemist from India or buy it in Spain, Mexico, the Mideast and Far East where an Rx is not needed.
This may be more than you wish to know. Can you tell I am stuck in an airport half way round the world? Anyway, good luck