If you spend wisely, it’s better to spend everything on CC. This is what I did:

Both free cards: Tandem Credit card 0.5% cashback mastercard for everywhere that doesn’t accept amex Amex everyday platinum credit card -5% cashback for 1st 3 months (maximum 100) thereafter 1%

Top picks for bank accounts would be Natwest Rewards current account that provides cashback (I believe 2%) on all bills. It’s 2 pound a month but with all my bills i usually get 6 quid a month minus the fee. It does depend on a lot of bills going out by DD.

Nationwide flex direct is another favourite where you can get 5% interest if your balance is at least 2500 (basically a free 125) plus if a friend recommends you, you and them get a free 100 quid each. So potential 225 in first year. After first year rate drops to 1% but if you need 2500 in there for cash flow it’s 2 quid for doing nothing.