Credit Score isn't really a thing in the UK. In the US it is huge and the score is the important thing. In the UK each agency looking to lend you money will have their own criteria which they will get from your credit report. The score is just a number calculated based off your report and different credit agencies calculate it differently.
Typically what a lender is looking for is a history of paying your debts reliably although some companies see this as a negative because there is no money in it for them if you do. I get 0% credit cards to pay my annual things like home insurance up front. The credit card companies don't make a penny off me in interest but they do get a % when I make purchases so they want to see high credit usage with reliable repayments. You can make your score go up artificially by taking out credit cards with large limits and never closing them. Some lenders would see that as a positive because you aren't exceeding your credit limit and others would see it as a negative (access to large amount of credit that they wouldn't be able to repay).
The only thing you want to make sure is that you don't have a load of searches at key times like when applying for a mortgage. Every time you apply for credit the lender will do a search on your file. Lots at once makes it look like you might be desperate for credit which they see as a negative.
