I have a not impressive credit rating - I don’t know why as I have no debts - one late payment in 2017
Should I get a credit card just to bump my figures up?
I’ve no intention of using it
If you get a credit card then you have to use it for it to have any effect on your Credit rating. Spend on it and pay it off completely each month -don't leave a balance. Also anything you can pay with by Direct Debit do so -this impact positively on your rating. If you don't know why you have a low rating then I suggest signing on here and finding out -it also gives you tips on how to increase your rating and offers on cards.
https://www.clearscore.com/
Your Credit rating is used for all sorts of things -not just credit. Insurance companies do soft searches, even sometimes potential employers -it's not just used to get credit.
I think if you do a pre-application check it won't impact your rating. (many cards do this). Cards like Ocean specialise in poor credit rated customers - with a low spending limit £1500.
I have no debts & a single credit card that I pay in full each month.
A mate of mine is up to his ears in debt - numerous credit cards & buy now/pay later purchases. He does frequent balance transfers and pays the minimum required each month. He has a better credit rating than I do!