Not having a credit score isn't necessarily a big problem, as banks use it for context rather than making decisions purely based on it, but I did see some advice online about getting a "credit builder card" [1] (essentially a high interest and low credit limit card) as a way to build up credit history.
I decided that getting in debt just so I can prove I can get out of it is a stupid system, and didn't do it. Last time I checked (with Experian), I had a perfect credit score, so I don't know what happened in the meantime.
1: https://www.experian.co.uk/consumer/credit-cards/types/credi...
From your nickname it sounds like you are from Romania so if that's so there might be a dose of xenofobia included there as well. That is kinda big in the UK right now, the whole Brexit was fuelled by it, sadly, especially concerning eastern Europe. I was on the receiving end of some of it myself too, being called 'a non-national' and eyed with distrust. I'm sorry.