Alternative to a copper cylinder

maybe swap too a combi boiler ?

Cylinders are very tried and tested, with low maintenance. I would only fit stainless as some of the copper are now very poor.

Replacing your boiler with a combi boiler can be a good solution, but you could be looking at €5k vs €1k for the new cylinder.

Very little in the circumstances you describe and if you are happy with your electric shower.

(With a combi boiler, you could get rid of the cylinder altogether. You could replace the electric shower with a power shower which would deliver 3 times the flow rate of the current electric shower.) But there are much lower cost ways of upgrading the shower to deliver the same performance off a cylinder if that was a desire.

I did this, combi boiler with a buffer tank.
Then had the hot water cylinder removed and reconfigured the hot press into storage with a hanging rail.
I put a small rad and a dehumidifier in there for occasional hang to dry use, that my Mrs has decided is brilliant.

What type of central heating do you have? I'm on gas, like you I had a small leak in the cylinder. Then boiler went kaput, so I replaced both with a combi boiler.

Heating works as it always did (I'm hoping for more efficient bills!) and I have instant hot water from taps. I also have an electric shower, so I don't need a lot of other hot water (but I had to heat a cylinder full when I did need some prior to the change).

I also have extra storage space instead of my hot pressure.

Thanks a mil for that! Showed the missus and she is intrigued 😁must have been handy to stick that rad in with all the piping work there already.