Hi can you please recommend the safest PORTA COT for travelling with a 6 month old?

Red Nose does not recommend specific brand name products like porta - cots.
A safe porta - cot is one that meets mandatory Australian standards. (AS/NZS 2195)
https://www.productsafety.gov.au/products/babies-kids/kids-furniture/folding-cots

Red Nose has some important information when using your porta cot.
Only use the firm, thin, well-fitting mattress that is supplied with the portable cot.
Never add a second mattress or additional padding under or over the mattress, which has been specifically designed for the portacot, as baby may become trapped face down in gaps between the mattress and the sides.

Do not use a portable cot if your child weighs more than 15kg (or check instructions of your particular model).
https://rednose.org.au/article/portable-cots