Various regular savers as mentioned about at the moment offering good rates. They are limited to small amounts per month so you can only stash away a few grand in a year, but still.
Some offer big rates but a lower monthly limit, some lower and a bit more. Then there may be withdrawal limits or not. Often limited to a year also.
I’m on a Nationwide regular with 2% but max of £500 a month and unlimited withdrawals, instant access.
Stocks and shares ISAs… just be wary of the risks. Even spreading about I’ve found the returns have been lousy, or have to keep it locked up for 20 years and realised I could have got a better return in plain savings over a shorter term. If you want to make decent money from stocks and shares, you need to properly get into trading and be prepared to move things about frequently, keep an eye on the markets, etc.
Personally I’d concentrate on debts. Can you overpay on the mortgage? If so chuck money at it. You can make massive savings on the mortgage that way. A decent mortgage will let you borrow back the overpayments also so you still have funds for emergencies, but ideally you’ll be repaying the mortgage early.