I've just left the company where I worked for 5 years. I've just left the company where I worked for 5 years.

I've just left the company I worked at for 5 years. I've just left the company I worked at for 5 years.

My last day of the company is officially as of April 30th, but I am already on the holidays. My last day of the company is officially April 30th, but I am already on the holiday.

My last day ofat the company is officially as of April 30th, but I am already on the holidays. My last day at the company is officially April 30th, but I am already on holiday.

"On holiday" is "on vacation" in American English.

If there whadn't thebeen a virusal pandemic, I would have been gone foron a trip right now... If there hadn't been a viral pandemic, I would have been gone on a trip right now...

"Virus" as adjective = "viral." "If" clauses should either be in the imperfect ("if there weren't"), the present ("if there wasn't"), or the past perfect ("if there hadn't been"). This is also affected by the tense that you want to use for the independent clause and by the connotation: https://www.ef.edu/english-resources/english-grammar/conditional/

If there wadsn't the virus pandemic, I would have gone foron a trip right now... If there wasn't the virus pandemic, I would have gone on a trip right now...

I should mention that, while this is technically correct, there are other ways to say it that sound more natural. Here's how I would say it: "If it weren't for the pandemic, I would be on a trip right now..."

Instead of travelling around, I'm staying at home reading books, and watching TV and videos... Instead of travelling around, I'm staying at home reading books and watching TV and videos...

Since you used ellipsis, what you had wasn't strictly wrong, but when you only have two items on the list, it sounds more natural this way.

Instead of travelling around, I'm staying at home reading books, and watching TV and videos... Instead of travelling around, I'm staying at home reading books and watching TV and videos...

Now I'm so muchreally looking forward to starting a new job fromin May! Now I'm really looking forward to starting a new job in May!

"So much" sounds awkward here to me. If you wanted to use it though, you should put it after "looking forward": the order is "verb + so much," not "so much + verb." Here, you're discussing a specific point in time, because you're "starting" something, so you would use "in." "From" only works when you're discussing an extended period, and you'd want to complete the phrase with something to indicate the ending, like "from now on" or "from May onwards."

Now I'm so much looking forward so much to starting a new job fromin May! Now I'm looking forward so much to starting a new job in May!