Hallo, Martin. If you're aiming for the colloquial version of Bahasa Indonesia, you're doing really good!

The previous comment has given you good corrections if you want to be on the formal version.

Here are some additional tips if what you are targeting is to sound casual & like a local :)

Tamasya = Liburan (holiday / vacation).

berlibur = liburan (also means 'having a holiday' in colloquial / spoken Indonesian)

Kalau matahari terbit = ketika matahari terbit ("kalau" means "if", and "ketika" means "when". I don't think you meant to say "if the sun rises", since the sun does / will rise every day :)).

"banget" and "mau" = you can absolutely use these words in casual conversation :) here's to compare the different effects between banget vs. sekali and between mau vs. ingin:

Ah, cool, now I get it :) Since this is a lighthearted funny story, I give you options of the colloquial words in brackets (in <em>italic</em>) that you can use if you want to sound more casual, street-level conversation.

<s>Ikan gurita ada di rumah</s> Gurita di rumahku ("The octopus in my house") or Ada gurita di rumahku ("There's an octopus in my house")

Anak saya suka bermain (<em>main</em>) gitar. Dia <s>menpunya </s>mempunyai (<em>punya</em>) empat <s>batang </s>gitar. Tetapi (<em>Tapi</em>) saya <s>ada </s>mempunyai (<em>punya</em>) seorang anak <s>sahaja </s>saja. Saya <s>fikir </s>pikir, anak saya <s>mungin </s>mungkin (<em>jangan-jangan</em>, which means "could be") <s>ikan </s>gurita. <s>Ikan</s> Gurita di rumah saya sekarang sedang (<em>lagi</em>) bermain (<em>main</em>) <s>sebatang </s>gitar.