OK, 150 ml will get you out of trouble this time. But you need to continually strerilise when frames are removed from a colony. So you will need more eventually. Especially, as you only had the one colony and will surely realise the benefits of having at least two for easier beekeping.
One 'problem' is that the 5 l for 22 quid (plus delivery) is actually 6 l as 80% concentration is used for sterilisation and the acid supplied is glacial - near 100%.
The offshoot of that is that it will go solid at around 17 degrees, unless diluted. You could waste quite a bit and still be ahead of the game with regards bee keeper suppliers - one charges near 40 quid, for less than half as much, and you have to collect.
Standard method of dilution of concentrated acids is always pour acid into water. Standard safety measures are needed also.
80% is much safer than glacial - still nasty, but safer.
As posted previously, give a location; doesn't need to be a post code. Someone might help you out.
Regards, RAB