Argos, 24" TV with HDMI £139
https://www.argos.co.uk/product/9171693
Amazon VGA to HDMI converter/connector £15
https://www.amazon.co.uk/FOINNEX-VGA.../dp/B072KR7MJW
I've no idea if the above would be suitable for your needs, or the quality of the picture/audio . .
I'm throwing it in as a suggestion, and hoping others with better knowledge/experience of such things will be able to provide better answers.
Another thing to be aware of, is that the new TV will be 24" widescreen and therefore probably look smaller than the older 24" CRT type 4:3 TV/Monitor
edit Argos 24" Panasonic with VGA £119
https://www.argos.co.uk/product/7608546