We have the Avionaut Sky for our 2 year old which was recommended by Car Seat Safety UK Facebook page. I bought it from one of the sellers on there (well we bought 2-one for each car).
Highly recommend Car Seat Safety UK or Bump to Booster - UK Car Seat Support on FB. Recommendations all depend on the height/weight of your toddler and circumstances
I have a Joie i spin safe, it has a good adac rating & in Swedish plus tested, lasts to around 4 years
Avionaut Sky or Axkid Minikid, as suggested above join one of the Facebook groups and add your child’s details for personalised recommendations x
We love our BeSafe Twist/Turn. Swedish Plus rated. But ours is small for his age. Our parents gave the Joie spin but it’s lots bulkier and the clip is more awkward. If you need something that’ll last longer than Axkid/Avionaut
Axkid and other Swedish tested rear facing are the best - should last you till 7 🤞🏻🤞🏻