How Many Universities Do I Apply To For Early Decision?

I'm applying for Cambridge, Imperial, UCL, King's and Manchester for the 2025 in-take. Out of which, only Cambridge has early decision. Does that mean that my first application (the one with the deadline of October 15) will only include Cambridge as my univesity choice and that I will submit another application before the regular deadline (January, 2025) with my remaining 4 choices? Or can I submit one application with all 5 choices as part of early decision? Keep in mind that I will be sitting the ESAT for both Imperial and Cambridge, so does that have any effect? Any help is much appreciated, thank you.

I'm applying for Cambridge, Imperial, UCL, King's and Manchester for the 2025 in-take. Out of which, only Cambridge has early decision. Does that mean that my first application (the one with the deadline of October 15) will only include Cambridge as my univesity choice and that I will submit another application before the regular deadline (January, 2025) with my remaining 4 choices? Or can I submit one application with all 5 choices as part of early decision? Keep in mind that I will be sitting the ESAT for both Imperial and Cambridge, so does that have any effect? Any help is much appreciated, thank you.

UCAS can only be submitted once with 5 choices. So you have to submit 1 single Personal Statement for all 5 choices.
By KMI Uprep

The concept of early decision is an American one, but I understood your fundamental point.
You can apply to Cambridge by October and your other uni choices by Jan 2025. Oxford and Cambridge application schemes are unique due to their internal processes.
I suggest that you apply to 3 unis as early as you can i.e. Cambridge, UCL, Manchester to obtain some early offers. This would determine the unis that you add for the last 2 options by Jan 2025.
Finally, your uni options are too competitive. Be careful with applying to Cambridge, UCL, Imperial and King’s together as they are top unis. You should dilute the options with some others like Southampton, York, Newcastle, Uni of Birmingham, Sheffield etc.

I mostly agree with the previous commenter but yeah, 'early decision' isn't a thing in the UK. Cambridge (along with Oxford and some Medicine-aligned courses) have an early application deadline in October, meaning you have to submit your application in before this date, usually around October 15th.
For your other universities, generally the deadline is in January. You can choose to apply to all five at the same time or do one (or two, three, four etc.) earlier and the rest later. Regardless, your application will be the same for all your universities. Applying for some later just gives you more time to choose your options if you're still undecided. Since you've already decided, this is probably unnecessary.
I would agree that your choices are quite competitive but it may be overkill to apply to three and wait for them to get back to you before adding the others. If you don't get an offer from any of your five you can apply for an extra one or you can go into clearing in June, though this may reduce the number of options available. You may want to consider one more safety if you're definitely thinking of studying in the UK and don't want to risk getting no offers but if you have other options - e.g. a gap year or studying elsewhere - these are fine.

Thank you! But since I'm an international student, my whole concept of studying abroad is to either go to the top or don't bother going. If I go to a university on par with a local university, I don't see the point in paying extra money growing abroad. I know my choices are competitive, but it is either hit the nail or don't go for me! It's a risk I'm willing to take and I'm confident I'll get into at least one of them!

Oh, that makes completely sense and I agree. Good luck