A Malaysian passport (the red one) is what enables you to travel internationally. If you have that, yes, you can travel to London. I'm not sure what you mean by "international passport". You must ensure that your passport hasn't expired and that you have 6 months left before it expires at the point you want to go to London.

Perhaps you mean to ask if you require a visa. Some countries require you to have a visa in addition to your passport before you are allowed to enter their country. For your travel purposes, you do not need a visa to to go London.

An additional check that you may wish to do is to check if you are blacklisted from travelling out of Malaysia. Here is the link for you to check:
http://sspi2.imi.gov.my/

If all that is in order, go ahead and purchase your flight tickets.

Hi I am applying for the digital immigration and customs services for Japan
https://services.digital.go.jp/en/visit-japan-web/

When I submit the photo of my passport, it automatically populates the "given name" with my full name. The "surname" is left blank.

As far as I recall, it is the opposite for the Aussie ETA application.

I know that I couldn't make any changes for the Aussie ETA whereas I am able to do so for the Japan digital service.

Can anyone with experience advice if I should delete my surname in the "given name" field and insert it into the "surname" field? If it is relevant, I do have a first name and chinese name.

Thanks