Sprawdzenie listu nieformalnego :)

Witam,
Mam dość pilną sprawę, gdyż napisałam list do szkoły i nie jestem pewna czy nie ma tam żadnych błędów, jeśli ktoś by znalazł czas, bardzo prosze o jego sprawdzenie :)
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Dear Auntie,
I'm happy you finally wrote to me. I hope you're doing fine.

Really thanks for your invitation but unluckily I've already had plans since about previous holiday and I can't change it, sorry.

These days I'm going with my friends to London. It'll be awesome. Mom let me go alone, that was big surprise. The best thing about it's that my cruch's going there too!

I hope you aren't mad for me. Maybe I can drop in after my trip? Suggest term. I'll promise next time I come :)

Love you,
XYZ

I'm happy THAT you finally wrote to me.
'Really' (to jest zle slowo - za bardzo tlumaczysz z jez. polskiego slowo w slowo - tutaj moze byc 'Grateful') thanks for your invitation (przecinek przed 'but') but 'unluckily' (zle slowo) I've already 'had' (zle slowo, tutaj daj 'zrobilem') plans 'since' (calkowicie zle slowo) 'about' (nie rozumiem tego) previous holiday and I can't change 'it' (zle 'plans' to jest l. mnoga - popraw), sorry.

'These days' (zle mpojecie - nie wiem co chcesz powiedziec) I'm going with my friends to London. Mom let me go alone, that was (a gdzie przedimek?) big surprise. The best thing about 'it's' (tu maja byc 2 slowa - popraw) that my 'cruch's' (nie rozumiem tego slowa) going there too!

I hope you aren't mad 'for' (calkowicie zle slowo - kalka z polskiego daj tutaj AT) me. Maybe I can drop in after my trip? (ale kto to ma zrobic? musisz napisac) suggest term. I'll promise THAT next time I (daj tu modala) come :)