The Amex Gold (technically Preferred Rewards Gold Credit Card) is a more affordable alternative to the Amex Platinum card. Free for the first year and then £195/year and 25,000 sign-up bonus points, it already provides some serious value. You can currently squeeze an extra £70 in cashback by applying through TopCashBack. And if you don’t have a TopCashback account, the link below offers a small sign-up bonus there as well.

After that, https://www.topcashback.co.uk/american-express will show you the current offers. Right now, the Amex Gold offers £70:

We have a dedicated page comparing the Gold and the Platinum card here. Be mindful that once you get the Gold Card you will no longer be eligible for the Platinum sign-up bonus, should you later decide to switch.