Sorry, boiler advice needed.

Hi all, It seems i have parental responsibility to insure there is enough hot water for my girls to be able to shower before school now they are growing up, so thats me the wife & two kids all fighting for the shower in the morning. We have a power shower that obviously uses more water than strictly needed, but I do love it & would hate to lose it, our main problem is the water runs out after 2 showers, the water is obviously recovering in to the tank & diluting the remaining water so its tepid at best by the third shower.
As I see it we have three options, one getting a bigger hot water tank, two switch to an electric shower, or three go the whole hog & get a combi.

So any advice from anyone who has had the same problem?
What sort of money should I expect to pay for having a combi fitted?
And finally can anyone recommend a decent plumber in hertfordshire?

Many thanks in advance, & sorry about the dullness of the question.
Cheers.

Weve got an electric shower at our uni house and its ace, theres 4 people showering 2x a day usually and never a problem.

at home i have the same problem as you though, I hate cold showers 🙁

Cheapest option would be electric. If you’ve got decent water pressure a 10kw should be getting on for power shower shower power.

Do you have an immersion heater in the tank?
You could use it with the boiler to heat the water quicker for the second two showers.

Don’t go with a combi boiler. Not at all suitable for all the showers plus heating if you have a reasonable sized house. Electric showers are not going to be a good as a proper power shower unless you want to burn huge amounts of electric. Depending on how much room you have, the easiest/quickest solution would be either a bigger tank, or simply a second tank sitting alongside which would have the same effect. If you go for a new tank, go Megaflow

Tanks for all the replies, some food for thought there, a bigger or second tank would probably be the cheapest way, but the boiler is old, no idea how old as its been here since we moved in 13 years ago, so now may be the time to change.
Cheers.