Is that a normal thing with BTC traders or is blockchain just specific about limits?
Each exchange methods has unique attributes.
In the UK, you probably want to look at Transferwise and/or CurrencyFair and then look at an exchange that takes Euro. That way you convert GBP to EUR using Transferwise or CurrencyFair, and then transfer the EUR to an exchange (e.g., BITSTAMP) and make your trades there.