A Fruit Sandwich

I ate a strawberries Sandwich as my desert instrawberry sandwich for dessert after dinner tonightonight.

The subject is a singular (1) sandwich with may strawberries in it - the flavour of the sandwich. Dessert (2 s's) = sweet. Desert (1 s) = dry arid land. The subject is "I", so you don't need to say "as my desert", you can simply write the meal it was for. Usually, we eat desert after dinner.

My dad and siblings went out, and they bought strawberriesstrawberry sandwiches as a souvenirtreat for my mom and meI.

As a collocation, we say "a treat" when referring to dessert. You could also say "My dad and siblings went out together and bought strawberry sandwiches as a treat" or "they bought strawberry sandwiches as a gift/surprise" if you did not know you were going to receive them. For proper grammar, we use "_____ and I". Shorter options: "My dad and siblings bought strawberry sandwiches for my mom and I." "When my dad and siblings went out, they bought strawberry sandwiches for my mom and I."

They are outdooroutdoorsy people, and my dad and my little brother played soccer for two hours right after they got home.

"outdoorsy" is an adjective to describe people who enjoy being outdoors.

I want the energy that much energy.

"I want (to have) that much energy." You are trying to shorten saying that you want to have as much energy as they do.

I'm too lazy to prepareget ready to go out, and so I tend to choose staying at home.

Prepare is a good word, but "get ready (to do something)" is a more natural collocation. We prepare for larger trips, for example, a vacation. "so," instead of "and" as a conjunction because you follow up will a reason or justification (a result) "I tend to choose staying at home". You can also say " I tend to stay at home" or "I tend to choose to stay (at) home."

However, I'm in theon summer holidays right now, so I think I should go outside on weekends.

"summer holidays" is good, but more British English - most North American English will use "summer vacation". If you are a student, you can use "summer break". "on weekends" or "during (the) weekends" - you need a preposition to be doing something within a fixed period of time.

I ate a strawberries Sandwichstrawberry sandwich as my desert indessert after dinner tonightonight.

It is not clear whether you ate the sandwich for dinner (in place of dessert) or skipped dinner to eat it as dessert instead.

My dad and siblings went out, and they bought strawberriesstrawberry sandwiches as a souvenirgifts for my mom and me.

They are outdoor people, and myMy dad and my little brother are outdoorsy people and played soccer for two hours right after they got home.

I want thetheir same energy that much.

You could also say "I wish I had that same energy"

I'm too lazy to prepare to go out and I tend to choose staying at home.

When two clauses in a sentence have the same subject, you don't have to repeat it. You could also say "...and prefer to stay at home".

However, I'm in theon summer holidaysholiday right now, so I think I should go outside on the weekends.

"I'm on summer holiday" for British English. "I'm on summer break (or summer vacation)" for American English.

I ate a strawberries Sandwichstrawberry sandwich as my desert indessert at dinner tonightonight.

"desert" = Sandy, dry region "dessert" = sweet food eaten in addition to a meal When ingredients are used as an adjective for a meal, they're _usually_ singular, but some specific dish names might use plural.

My dad and siblings went out, and they bought strawberriesstrawberry sandwiches as a souvenir for my mom and me.

They are outdoor people, and my dad and my little brother played soccer for two hours right after they got home.

You don't need to repeat "my" here

I want the energyto have that much energy.

"I want X that much" would be saying how much you want X, but you'd also need to pair it up with an actual example of how much you want it. If you want to say you want the same amount of energy as your dad and brother, it's better to use "that much" as a modifier to "energy"

I'm too lazy to prepare to go out and I tend to choose stayingto stay at home.

However, I'm in theon my summer holidays right now, so I think I should go outside on weekends.

I ate a strawberries Sandwichstrawberry sandwich as my desert indessert at dinner tonightonight.

My dad and siblings went out, and they bought strawberriesstrawberry sandwiches as a souvenirgift for my mom and me.

I want the energy that much energy.

However, I'm in the summer holidays right now, so I think I should go outside weekends.

No change suggested

In the USA we would say "I'm on summer vacation" or "I'm on summer break." I think your response may be correct in England, but I could be wrong.